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

/**
 * Created by trung.pham on 25/12/17.
 */
public class D_Edu_Round_33 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        int n = in.nextInt();
        int d = in.nextInt();
        long[]cur = new long[n];
        long[]data = new long[n];
        ArrayList<Integer> list = new ArrayList();
        for(int i = 0; i < n; i++){
            data[i] = in.nextInt();
            cur[i] += data[i];
            if(i > 0){
                cur[i] += cur[i - 1];
            }
            if(data[i] == 0){
                list.add(i);
            }

        }
      //  System.out.println ( Arrays.toString(cur));
        long[]max = new long[n];
        for(int i = n - 1; i >= 0; i --){
            max[i] = cur[i];
            if(i + 1 < n){
                max[i] = max(max[i], max[i + 1]);
            }
        }
      //  System.out.println(Arrays.toString(max) + " " + Arrays.toString(cur));
        int result = max[0] > d ? -1 : 0;
        long tmp = 0;
        for(int i = 0; i < list.size() && result != -1; i++){
            int index = list.get(i);
            long v = cur[index];
            if(v < 0){
                v = -v;
                if(tmp >= v){
                    v = 0;
                }else{
                    tmp = v;
                }
            }else{
                v = 0;
            }

            if(v == 0){
                continue;
            }
           // System.out.println(index);
            if(max[index] + v > d){
                result = -1;
            }else{
                long mx = max[index];
                result++;
                int nxt = i + 1;
                while(nxt < list.size()){
                    index = list.get(nxt);
                    v = cur[index];
                    if(v < 0){
                        v = -v;

                    }else{
                        v = 0;
                    }
                   // System.out.println(v + " " + mx);
                    if(v == 0 || tmp >= v){

                    }else{

                        if(mx + v > d){

                            break;
                        }else{
                            tmp = v;
                        }
                    }
                    nxt++;
                }
                i = --nxt;
            }
        }
        out.println(result);


        out.close();
    }

    static long max(long a, long b){
        return a < b ? b : a;
    }
}
