import java.io.*;
import java.util.*;

public class Main {
    static int mod = 1000000007;
    public static void main(String args[]) throws IOException {
        Scan sc = new Scan();
        int n = sc.scanInt();
        int[] stairs = new int[n+1];
        stairs[0]=1;
        int m = sc.scanInt();
        while(m-- > 0)
            stairs[sc.scanInt()]=-1;
        for(int i = 1; i <= n; ++i){
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        }
        System.out.println(stairs[n]);
        
    }
    
    static int modAdd(int a, int b){
        return (int)(((long)a+b)%mod);
    }
}

class Scan
{
    private byte[] buf=new byte[1024];
    private int index;
    private InputStream in;
    private int total;
    public Scan()
    {
        in=System.in;
    }
    public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    }
    public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public long scanLong() throws IOException {
        long integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    }
    public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    }
    private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    }
} import java.io.*; io.* java import java.util.*; util.* java public class Main {
    static int mod = 1000000007;
    public static void main(String args[]) throws IOException {
        Scan sc = new Scan();
        int n = sc.scanInt();
        int[] stairs = new int[n+1];
        stairs[0]=1;
        int m = sc.scanInt();
        while(m-- > 0)
            stairs[sc.scanInt()]=-1;
        for(int i = 1; i <= n; ++i){
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        }
        System.out.println(stairs[n]);
        
    }
    
    static int modAdd(int a, int b){
        return (int)(((long)a+b)%mod);
    }
} Main static int mod = 1000000007; mod 1000000007 public static void main(String args[]) throws IOException {
        Scan sc = new Scan();
        int n = sc.scanInt();
        int[] stairs = new int[n+1];
        stairs[0]=1;
        int m = sc.scanInt();
        while(m-- > 0)
            stairs[sc.scanInt()]=-1;
        for(int i = 1; i <= n; ++i){
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        }
        System.out.println(stairs[n]);
        
    } main {
        Scan sc = new Scan();
        int n = sc.scanInt();
        int[] stairs = new int[n+1];
        stairs[0]=1;
        int m = sc.scanInt();
        while(m-- > 0)
            stairs[sc.scanInt()]=-1;
        for(int i = 1; i <= n; ++i){
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        }
        System.out.println(stairs[n]);
        
    } Scan sc = new Scan(); sc new Scan() int n = sc.scanInt(); n sc.scanInt() sc.scanInt sc int[] stairs = new int[n+1]; stairs new int[n+1] n+1 n 1 stairs[0]=1 stairs[0] stairs 0 1 int m = sc.scanInt(); m sc.scanInt() sc.scanInt sc while(m-- > 0)
            stairs[sc.scanInt()]=-1; m-- > 0 m-- m 0 stairs[sc.scanInt()]=-1 stairs[sc.scanInt()] stairs sc.scanInt() sc.scanInt sc -1 1 for(int i = 1; i <= n; ++i){
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        } int i = 1; int i = 1; i 1 i <= n i n ++i ++i i {
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        } {
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        } if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            } stairs[i] == -1 stairs[i] stairs i -1 1 continue; {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            } int prev = Math.max(0, stairs[i-1]); prev Math.max(0, stairs[i-1]) Math.max Math 0 stairs[i-1] stairs i-1 i 1 int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0); pprev (i>=2 ? Math.max(0, stairs[i-2]):0) i>=2 i 2 Math.max(0, stairs[i-2]) Math.max Math 0 stairs[i-2] stairs i-2 i 2 0 stairs[i] = modAdd(prev, pprev) stairs[i] stairs i modAdd(prev, pprev) modAdd prev pprev System.out.println(stairs[n]) System.out.println System.out System System.out stairs[n] stairs n String args[] args static int modAdd(int a, int b){
        return (int)(((long)a+b)%mod);
    } modAdd {
        return (int)(((long)a+b)%mod);
    } return (int)(((long)a+b)%mod); (int)(((long)a+b)%mod) ((long)a+b) (long)a b mod int a a int b b class Scan
{
    private byte[] buf=new byte[1024];
    private int index;
    private InputStream in;
    private int total;
    public Scan()
    {
        in=System.in;
    }
    public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    }
    public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public long scanLong() throws IOException {
        long integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    }
    public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    }
    private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    }
} Scan private byte[] buf=new byte[1024]; buf new byte[1024] 1024 private int index; index private InputStream in; in private int total; total public Scan()
    {
        in=System.in;
    } Scan {
        in=System.in;
    } in=System.in in System.in System System.in public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    } scan {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    } if(total<0)
        throw new InputMismatchException(); total<0 total 0 throw new InputMismatchException(); new InputMismatchException() if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        } index>=total index total {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        } index=0 index 0 total=in.read(buf) total in.read(buf) in.read in buf if(total<=0)
            return -1; total<=0 total 0 return -1; -1 1 return buf[index++]; buf[index++] buf index++ index public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    } scanInt {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    } int integer=0; integer 0 int n=scan(); n scan() scan while(isWhiteSpace(n))
        n=scan(); isWhiteSpace(n) isWhiteSpace n n=scan() n scan() scan int neg=1; neg 1 if(n=='-')
        {
            neg=-1;
            n=scan();
        } n=='-' n '-' {
            neg=-1;
            n=scan();
        } neg=-1 neg -1 1 n=scan() n scan() scan while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException(); n>='0'&&n<='9' n>='0' n '0' n<='9' n '9' {
                integer*=10;
                integer+=n-'0';
                n=scan();
            } integer*=10 integer 10 integer+=n-'0' integer n-'0' n '0' n=scan() n scan() scan throw new InputMismatchException(); new InputMismatchException() return neg*integer; neg*integer neg integer public long scanLong() throws IOException {
        long integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    } scanLong {
        long integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    } long integer=0; integer 0 int n=scan(); n scan() scan while(isWhiteSpace(n))
        n=scan(); isWhiteSpace(n) isWhiteSpace n n=scan() n scan() scan int neg=1; neg 1 if(n=='-')
        {
            neg=-1;
            n=scan();
        } n=='-' n '-' {
            neg=-1;
            n=scan();
        } neg=-1 neg -1 1 n=scan() n scan() scan while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException(); n>='0'&&n<='9' n>='0' n '0' n<='9' n '9' {
                integer*=10;
                integer+=n-'0';
                n=scan();
            } integer*=10 integer 10 integer+=n-'0' integer n-'0' n '0' n=scan() n scan() scan throw new InputMismatchException(); new InputMismatchException() return neg*integer; neg*integer neg integer public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    } scanDouble {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    } double doub=0; doub 0 int n=scan(); n scan() scan while(isWhiteSpace(n))
        n=scan(); isWhiteSpace(n) isWhiteSpace n n=scan() n scan() scan int neg=1; neg 1 if(n=='-')
        {
            neg=-1;
            n=scan();
        } n=='-' n '-' {
            neg=-1;
            n=scan();
        } neg=-1 neg -1 1 n=scan() n scan() scan while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } !isWhiteSpace(n)&&n!='.' !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n n!='.' n '.' {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        } if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException(); n>='0'&&n<='9' n>='0' n '0' n<='9' n '9' {
                doub*=10;
                doub+=n-'0';
                n=scan();
            } doub*=10 doub 10 doub+=n-'0' doub n-'0' n '0' n=scan() n scan() scan throw new InputMismatchException(); new InputMismatchException() if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        } n=='.' n '.' {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        } n=scan() n scan() scan double temp=1; temp 1 while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            } !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            } if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException(); n>='0'&&n<='9' n>='0' n '0' n<='9' n '9' {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                } temp/=10 temp 10 doub+=(n-'0')*temp doub (n-'0')*temp (n-'0') n '0' temp n=scan() n scan() scan throw new InputMismatchException(); new InputMismatchException() return doub*neg; doub*neg doub neg public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    } scanString {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    } StringBuilder sb=new StringBuilder(); sb new StringBuilder() int n=scan(); n scan() scan while(isWhiteSpace(n))
        n=scan(); isWhiteSpace(n) isWhiteSpace n n=scan() n scan() scan while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        } !isWhiteSpace(n) isWhiteSpace(n) isWhiteSpace n {
            sb.append((char)n);
            n=scan();
        } sb.append((char)n) sb.append sb (char)n n=scan() n scan() scan return sb.toString(); sb.toString() sb.toString sb private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    } isWhiteSpace {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    } if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true; n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1 n=='\t' n=='\r' n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1 n==' ' n ' ' n=='\n' n '\n' n=='\r' n '\r' n=='\t' n '\t' n==-1 n -1 1 return true; true return false; false int n n public class Main {
    static int mod = 1000000007;
    public static void main(String args[]) throws IOException {
        Scan sc = new Scan();
        int n = sc.scanInt();
        int[] stairs = new int[n+1];
        stairs[0]=1;
        int m = sc.scanInt();
        while(m-- > 0)
            stairs[sc.scanInt()]=-1;
        for(int i = 1; i <= n; ++i){
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        }
        System.out.println(stairs[n]);
        
    }
    
    static int modAdd(int a, int b){
        return (int)(((long)a+b)%mod);
    }
} public class Main {
    static int mod = 1000000007;
    public static void main(String args[]) throws IOException {
        Scan sc = new Scan();
        int n = sc.scanInt();
        int[] stairs = new int[n+1];
        stairs[0]=1;
        int m = sc.scanInt();
        while(m-- > 0)
            stairs[sc.scanInt()]=-1;
        for(int i = 1; i <= n; ++i){
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        }
        System.out.println(stairs[n]);
        
    }
    
    static int modAdd(int a, int b){
        return (int)(((long)a+b)%mod);
    }
} Main
import java.io.*;
import java.util.*;

public class Main {
    static int mod = 1000000007;
    public static void main(String args[]) throws IOException {
        Scan sc = new Scan();
        int n = sc.scanInt();
        int[] stairs = new int[n+1];
        stairs[0]=1;
        int m = sc.scanInt();
        while(m-- > 0)
            stairs[sc.scanInt()]=-1;
        for(int i = 1; i <= n; ++i){
            if(stairs[i] == -1)
                continue;
            else {
                int prev = Math.max(0, stairs[i-1]);
                int pprev = (i>=2 ? Math.max(0, stairs[i-2]):0);
                stairs[i] = modAdd(prev, pprev);
            }
        }
        System.out.println(stairs[n]);
        
    }
    
    static int modAdd(int a, int b){
        return (int)(((long)a+b)%mod);
    }
}

class Scan
{
    private byte[] buf=new byte[1024];
    private int index;
    private InputStream in;
    private int total;
    public Scan()
    {
        in=System.in;
    }
    public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    }
    public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public long scanLong() throws IOException {
        long integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    }
    public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    }
    private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    }
}
