import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.PriorityQueue;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.HashSet;
import java.math.BigDecimal;

public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        long a = fs.nextLong();
        double b = fs.nextDoutble();
     	BigDecimal b1 = BigDecimal.valueOf(a);
	    BigDecimal b2 = new BigDecimal(String.valueOf(b));
	    BigDecimal t3 = (b1.multiply(b2));
        System.out.println(t3.longValue()); 

        
  }
  public static int calcMin(int[] array) {

    int intMin = array[0];

    for (int i = 1; i < array.length; i++ ) {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    }
    return intMin;
}
}
class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte(){
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <=0){
                return false;
            }
        }
        return true;
    }

    private int readByte(){
        if(hasNextByte())return buffer[ptr++];
        else return -1;
    }

    private static boolean isPrintableChar(int c){
        return 33<=c && c<=126;
    }
    public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr]))ptr++;
        return hasNextByte();
    }

    public String next(){
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong(){
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b<='9'){
                n*=10;
                n+=b-'0';
            }else if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt(){
        long nl = nextLong();
        if(nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDoutble(){return Double.parseDouble(next());}
} import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.util.ArrayList; ArrayList java.util import java.util.Arrays; Arrays java.util import java.util.Comparator; Comparator java.util import java.util.LinkedList; LinkedList java.util import java.util.List; List java.util import java.util.NoSuchElementException; NoSuchElementException java.util import java.util.PriorityQueue; PriorityQueue java.util import java.util.ArrayDeque; ArrayDeque java.util import java.util.Queue; Queue java.util import java.util.HashSet; HashSet java.util import java.math.BigDecimal; BigDecimal java.math public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        long a = fs.nextLong();
        double b = fs.nextDoutble();
     	BigDecimal b1 = BigDecimal.valueOf(a);
	    BigDecimal b2 = new BigDecimal(String.valueOf(b));
	    BigDecimal t3 = (b1.multiply(b2));
        System.out.println(t3.longValue()); 

        
  }
  public static int calcMin(int[] array) {

    int intMin = array[0];

    for (int i = 1; i < array.length; i++ ) {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    }
    return intMin;
}
} Main public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        long a = fs.nextLong();
        double b = fs.nextDoutble();
     	BigDecimal b1 = BigDecimal.valueOf(a);
	    BigDecimal b2 = new BigDecimal(String.valueOf(b));
	    BigDecimal t3 = (b1.multiply(b2));
        System.out.println(t3.longValue()); 

        
  } main {
        FastScanner fs = new FastScanner();
        long a = fs.nextLong();
        double b = fs.nextDoutble();
     	BigDecimal b1 = BigDecimal.valueOf(a);
	    BigDecimal b2 = new BigDecimal(String.valueOf(b));
	    BigDecimal t3 = (b1.multiply(b2));
        System.out.println(t3.longValue()); 

        
  } FastScanner fs = new FastScanner(); fs new FastScanner() long a = fs.nextLong(); a fs.nextLong() fs.nextLong fs double b = fs.nextDoutble(); b fs.nextDoutble() fs.nextDoutble fs BigDecimal b1 = BigDecimal.valueOf(a); b1 BigDecimal.valueOf(a) BigDecimal.valueOf BigDecimal a BigDecimal b2 = new BigDecimal(String.valueOf(b)); b2 new BigDecimal(String.valueOf(b)) BigDecimal t3 = (b1.multiply(b2)); t3 (b1.multiply(b2)) b1.multiply b1 b2 System.out.println(t3.longValue()) System.out.println System.out System System.out t3.longValue() t3.longValue t3 String[] args args public static int calcMin(int[] array) {

    int intMin = array[0];

    for (int i = 1; i < array.length; i++ ) {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    }
    return intMin;
} calcMin {

    int intMin = array[0];

    for (int i = 1; i < array.length; i++ ) {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    }
    return intMin;
} int intMin = array[0]; intMin array[0] array 0 for (int i = 1; i < array.length; i++ ) {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    } int i = 1; int i = 1; i 1 i < array.length i array.length array array.length i++ i++ i {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    } {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    } if(intMin > array[i]) {
            intMin = array[i];
        } intMin > array[i] intMin array[i] array i {
            intMin = array[i];
        } intMin = array[i] intMin array[i] array i return intMin; intMin int[] array array class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte(){
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <=0){
                return false;
            }
        }
        return true;
    }

    private int readByte(){
        if(hasNextByte())return buffer[ptr++];
        else return -1;
    }

    private static boolean isPrintableChar(int c){
        return 33<=c && c<=126;
    }
    public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr]))ptr++;
        return hasNextByte();
    }

    public String next(){
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong(){
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b<='9'){
                n*=10;
                n+=b-'0';
            }else if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt(){
        long nl = nextLong();
        if(nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDoutble(){return Double.parseDouble(next());}
} FastScanner private final InputStream in = System.in; in System.in System System.in private final byte[] buffer = new byte[1024]; buffer new byte[1024] 1024 private int ptr = 0; ptr 0 private int buflen = 0; buflen 0 private boolean hasNextByte(){
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <=0){
                return false;
            }
        }
        return true;
    } hasNextByte {
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <=0){
                return false;
            }
        }
        return true;
    } if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <=0){
                return false;
            }
        } ptr < buflen ptr buflen {
            return true;
        } return true; true {
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <=0){
                return false;
            }
        } ptr = 0 ptr 0 try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            } catch(IOException e){
                e.printStackTrace();
            } IOException e {
                e.printStackTrace();
            } e.printStackTrace() e.printStackTrace e {
                buflen = in.read(buffer);
            } buflen = in.read(buffer) buflen in.read(buffer) in.read in buffer if(buflen <=0){
                return false;
            } buflen <=0 buflen 0 {
                return false;
            } return false; false return true; true private int readByte(){
        if(hasNextByte())return buffer[ptr++];
        else return -1;
    } readByte {
        if(hasNextByte())return buffer[ptr++];
        else return -1;
    } if(hasNextByte())return buffer[ptr++];
        else return -1; hasNextByte() hasNextByte return buffer[ptr++]; buffer[ptr++] buffer ptr++ ptr return -1; -1 1 private static boolean isPrintableChar(int c){
        return 33<=c && c<=126;
    } isPrintableChar {
        return 33<=c && c<=126;
    } return 33<=c && c<=126; 33<=c && c<=126 33<=c 33 c c<=126 c 126 int c c public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr]))ptr++;
        return hasNextByte();
    } hasNext {
        while(hasNextByte() && !isPrintableChar(buffer[ptr]))ptr++;
        return hasNextByte();
    } while(hasNextByte() && !isPrintableChar(buffer[ptr]))ptr++; hasNextByte() && !isPrintableChar(buffer[ptr]) hasNextByte() hasNextByte !isPrintableChar(buffer[ptr]) isPrintableChar(buffer[ptr]) isPrintableChar buffer[ptr] buffer ptr ptr++ ptr return hasNextByte(); hasNextByte() hasNextByte public String next(){
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } next {
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } if(!hasNext()) throw new NoSuchElementException(); !hasNext() hasNext() hasNext throw new NoSuchElementException(); new NoSuchElementException() StringBuilder sb = new StringBuilder(); sb new StringBuilder() int b = readByte(); b readByte() readByte while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        } isPrintableChar(b) isPrintableChar b {
            sb.appendCodePoint(b);
            b = readByte();
        } sb.appendCodePoint(b) sb.appendCodePoint sb b b = readByte() b readByte() readByte return sb.toString(); sb.toString() sb.toString sb public long nextLong(){
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b<='9'){
                n*=10;
                n+=b-'0';
            }else if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    } nextLong {
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b<='9'){
                n*=10;
                n+=b-'0';
            }else if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    } if(!hasNext()) throw new NoSuchElementException(); !hasNext() hasNext() hasNext throw new NoSuchElementException(); new NoSuchElementException() long n = 0; n 0 boolean minus = false; minus false int b = readByte(); b readByte() readByte if(b == '-'){
            minus = true;
            b = readByte();
        } b == '-' b '-' {
            minus = true;
            b = readByte();
        } minus = true minus true b = readByte() b readByte() readByte if(b < '0' || '9' < b){
            throw new NumberFormatException();
        } b < '0' || '9' < b b < '0' b '0' '9' < b '9' b {
            throw new NumberFormatException();
        } throw new NumberFormatException(); new NumberFormatException() while(true){
            if('0' <= b && b<='9'){
                n*=10;
                n+=b-'0';
            }else if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        } true {
            if('0' <= b && b<='9'){
                n*=10;
                n+=b-'0';
            }else if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        } if('0' <= b && b<='9'){
                n*=10;
                n+=b-'0';
            }else if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            } '0' <= b && b<='9' '0' <= b '0' b b<='9' b '9' {
                n*=10;
                n+=b-'0';
            } n*=10 n 10 n+=b-'0' n b-'0' b '0' if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            } b==-1 || !isPrintableChar(b) b==-1 b -1 1 !isPrintableChar(b) isPrintableChar(b) isPrintableChar b {
                return minus ? -n : n;
            } return minus ? -n : n; minus ? -n : n minus -n n n {
                throw new NumberFormatException();
            } throw new NumberFormatException(); new NumberFormatException() b = readByte() b readByte() readByte public int nextInt(){
        long nl = nextLong();
        if(nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)throw new NumberFormatException();
        return (int) nl;
    } nextInt {
        long nl = nextLong();
        if(nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)throw new NumberFormatException();
        return (int) nl;
    } long nl = nextLong(); nl nextLong() nextLong if(nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)throw new NumberFormatException(); nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE nl < Integer.MIN_VALUE nl Integer.MIN_VALUE Integer Integer.MIN_VALUE nl > Integer.MAX_VALUE nl Integer.MAX_VALUE Integer Integer.MAX_VALUE throw new NumberFormatException(); new NumberFormatException() return (int) nl; (int) nl public double nextDoutble(){return Double.parseDouble(next());} nextDoutble {return Double.parseDouble(next());} return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        long a = fs.nextLong();
        double b = fs.nextDoutble();
     	BigDecimal b1 = BigDecimal.valueOf(a);
	    BigDecimal b2 = new BigDecimal(String.valueOf(b));
	    BigDecimal t3 = (b1.multiply(b2));
        System.out.println(t3.longValue()); 

        
  }
  public static int calcMin(int[] array) {

    int intMin = array[0];

    for (int i = 1; i < array.length; i++ ) {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    }
    return intMin;
}
} public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        long a = fs.nextLong();
        double b = fs.nextDoutble();
     	BigDecimal b1 = BigDecimal.valueOf(a);
	    BigDecimal b2 = new BigDecimal(String.valueOf(b));
	    BigDecimal t3 = (b1.multiply(b2));
        System.out.println(t3.longValue()); 

        
  }
  public static int calcMin(int[] array) {

    int intMin = array[0];

    for (int i = 1; i < array.length; i++ ) {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    }
    return intMin;
}
} Main
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.PriorityQueue;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.HashSet;
import java.math.BigDecimal;

public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        long a = fs.nextLong();
        double b = fs.nextDoutble();
     	BigDecimal b1 = BigDecimal.valueOf(a);
	    BigDecimal b2 = new BigDecimal(String.valueOf(b));
	    BigDecimal t3 = (b1.multiply(b2));
        System.out.println(t3.longValue()); 

        
  }
  public static int calcMin(int[] array) {

    int intMin = array[0];

    for (int i = 1; i < array.length; i++ ) {
        if(intMin > array[i]) {
            intMin = array[i];
        }
    }
    return intMin;
}
}
class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte(){
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <=0){
                return false;
            }
        }
        return true;
    }

    private int readByte(){
        if(hasNextByte())return buffer[ptr++];
        else return -1;
    }

    private static boolean isPrintableChar(int c){
        return 33<=c && c<=126;
    }
    public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr]))ptr++;
        return hasNextByte();
    }

    public String next(){
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong(){
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b<='9'){
                n*=10;
                n+=b-'0';
            }else if(b==-1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt(){
        long nl = nextLong();
        if(nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDoutble(){return Double.parseDouble(next());}
}
