9 13
6 14 19 5 -5 6 -10 20 8
 8 9
6 -1 5 -5 -8 -7 -8 -7
 10 7
-9 3 -4 -22 4 -17 0 -14 3 -2
 6 2
-2 3 0 -2 0 0
 5 10
-8 -24 0 -22 12
 5 13756
-2 -9 -10 0 10
 7 3
1 -3 0 3 -1 0 2
 9 9
-3 2 0 -2 -7 -1 0 5 3
 2 3
2 0
 19 78701
1 0 -1 0 -1 -1 0 1 0 -1 1 1 -1 1 0 0 -1 0 0
 5 4
-1 0 0 1 -1
 6 4
-1 0 2 -4 0 5
 20 23036
-1 1 -1 -1 -1 -1 1 -1 -1 0 0 1 1 0 0 1 0 0 -1 -1
 5 4
-1 0 -3 0 3
 12 82016
1 -2 -1 -1 -2 -1 0 -2 -1 1 -2 2
 7 4
-6 0 2 -3 0 4 0
 4 4
2 2 0 1
 6 1
-3 0 0 0 -2 3
 8 26
-4 9 -14 -11 0 7 23 -15
 20 23079
0 1 1 -1 1 0 -1 -1 0 0 1 -1 1 1 1 0 0 1 0 1
 1 1
1
 7 8555
-2 -3 -2 3 0 -2 0
 4 100
-100 0 -50 100
 3 14
12 12 -8
 1 1
2
 10 23
9 7 14 16 -13 -22 24 -3 -12 14
 8 11
12 -12 -9 3 -22 -21 1 3
 19 49926
-2 0 2 0 0 -2 2 -1 -1 0 0 0 1 0 1 1 -2 2 2
 16 76798
-1 11 -7 -4 0 -11 -12 3 0 -7 6 -4 8 6 5 -10
 9 5
-2 0 3 -4 0 4 -3 -2 0

-1
 -1
 1
 1
 1
 1
 -1
 2
 0
 1
 1
 -1
 1
 1
 1
 1
 -1
 1
 -1
 0
 0
 1
 1
 -1
 -1
 -1
 -1
 1
 1
 1


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

public class Main implements Runnable {
    FastScanner sc;
    PrintWriter pw;

    final class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner() {
            try {
                br = new BufferedReader(new InputStreamReader(System.in));
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        public long nlo() {
            return Long.parseLong(next());
        }

        public String next() {
            if (st.hasMoreTokens())
                return st.nextToken();
            try {
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                e.printStackTrace();
            }
            return st.nextToken();
        }

        public int ni() {
            return Integer.parseInt(next());
        }

        public String nli() {
            String line = "";
            if (st.hasMoreTokens())
                line = st.nextToken();
            else
                try {
                    return br.readLine();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            while (st.hasMoreTokens())
                line += " " + st.nextToken();
            return line;
        }

        public double nd() {
            return Double.parseDouble(next());
        }
    }

    public static void main(String[] args) throws Exception {
        new Thread(null, new Main(), "codeforces", 1 << 28).start();
    }

    public void run() {
        sc = new FastScanner();
        pw = new PrintWriter(System.out);
        solve();
        pw.flush();
        pw.close();
    }

    public long gcd(long a, long b) {
        return b == 0L ? a : gcd(b, a % b);
    }

    public long ppow(long a, long b, long mod) {
        if (b == 0L)
            return 1L;
        long tmp = 1;
        while (b > 1L) {
            if ((b & 1L) == 1)
                tmp *= a;
            a *= a;
            a %= mod;
            tmp %= mod;
            b >>= 1;
        }
        return (tmp * a) % mod;
    }

    public int gcd(int x, int y) {
        return y == 0 ? x : gcd(y, x % y);
    }

    //////////////////////////////////
    ///////////// LOGIC ///////////
    ////////////////////////////////

    public void solve() {
        int n=sc.ni();
        int d=sc.ni();
        int[] arr=new int[n];
        for(int i=0;i<n;i++)
            arr[i]=sc.ni();
        int sum=0,s=0;
        for(;s<n;s++)
        {
            sum+=arr[s];
            if(sum>d)
            {
                pw.println(-1);
                return;
            }
            if(arr[s]==0&&sum<0)
                break;
        }
        if(s==n)
        {
            pw.println(0);
            return;
        }
        pw.println(solution(arr,s,n,d));

    }
    public int solution(int[] arr,int s,int e,int d)
    {
        int ans=1;
        List<Integer> list=new ArrayList<>();
        List<Integer> list1=new ArrayList<>();
        for(int i=s+1;i<e;i++)
        {
            int tmp=0,j=i;
            int max=0;
            while(!((j>=e)||(arr[j]==0&&tmp<0)))
            {
                tmp+=arr[j];
                max=Math.max(max,tmp);
                if(max>d)
                    return -1;
                j++;
            }
            if(j<e)
            {
                list.add(max);
                list1.add(tmp);
            }
            i=j;
        }
        for(int i=0;i<list.size();i++)
        {
            int max=Integer.MAX_VALUE;
            int req=0;
            int added=0;
            while(i<list.size())
            {
                if(list.get(i)+added>d)
                {
                    ans++;
                    break;
                }
                list.set(i,list.get(i)+added);
                list1.set(i,list1.get(i)+added);
                max=Math.min(max,d-list.get(i));
                if(list1.get(i)>=0)
                    continue;
                int hold=-1*list1.get(i);
                if(hold>max)
                {
                    ans++;
                    break;
                }
                max-=(hold);
                added+=(hold);
                req=Math.max(req,hold);                
                i++;
            }
        }
        return ans;
    }
}