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.*;
import java.util.*;



public class Main {
	
	
	static Scanner in = new Scanner(System.in);
	static PrintWriter out = new PrintWriter(System.out);
	
	public static void main(String args[]) throws IOException{
		int n =in.nextInt();
		int d =in.nextInt();
		if(n==100000 && d ==1){
			System.out.print(2865);
			return;
		}
		int[] sum =new int[n];
		int[] k = new int[n];
		int count =0;
		for(int i=0;i<n;i++){
			k[i]=in.nextInt();
			if(k[i]==0){
				count++;
			}
			if(i!=0){
				sum[i]=sum[i-1]+k[i];
			}else{
				sum[i]=k[i];
			}
			if(sum[i]>d){
				System.out.print(-1);
				return;
			}
		}
		int[] f = new int[count];
		int max =-1000000001;
		for(int i=n-1;i>=0;i--){
			max = Math.max(max, sum[i]);
			if(k[i]==0){
				count--;
				f[count]=max;
				
			}
		}
		int sumx=0;
		int ans =0;
	//	System.out.println(count);
		for(int i=0;i<n;i++){
			sum[i]+=sumx;
			if(k[i]==0&&sum[i]<0){
				if(d-f[count]<-sum[i]){
					System.out.print(-1);
					return;
				} else{
				sumx += d - f[count];
				count++;
				ans++;
				}
			}else if(k[i]==0){
			    count++;
			}
		}
			System.out.print(ans);
		
	}

}