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 CreditCard {
    public static void main(String[] args) throws IOException{
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        StringTokenizer st = new StringTokenizer(f.readLine());
        int n = Integer.parseInt(st.nextToken());
        long d = Integer.parseInt(st.nextToken());
        long[] arr = new long[n];
        st = new StringTokenizer(f.readLine());
        for(int i = 0; i < n; i++){
            arr[i] = Long.parseLong(st.nextToken());
        }
        long balance = 0;
        int count = 0;
        long[] balances = new long[n];
        long[] rightmax = new long[n];
        for(int i = 0; i < n; i++){
            balances[i] = balance;
            balance += arr[i];

            if(balance > d){
                out.println(-1);
                out.close();
                System.exit(0);
            }
        }
        rightmax[n-1] = balances[n-1];
        for(int i = n-2; i >= 0; i--){
            rightmax[i] = Math.max(rightmax[i+1], balances[i]);
        }
        balance = 0;
        int delta = 0;
        for(int i = 0; i < n; i++){
            if(balance < 0 && arr[i] == 0){
                count++;
                long tempDelta = d-(delta+rightmax[i]);
                if(tempDelta < 0){
                    out.println(-1);
                    out.close();
                    System.exit(0);
                }
                delta+=tempDelta;
                balance+=tempDelta;
            }
            balance+=arr[i];
        }
        out.println(count);
        out.close();
    }
}
