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

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#define ll long long
#define cheetah ios_base::sync_with_stdio(NULL);cin.tie(0);cout.tie(0)
#define deb1(x) cout<<"["#x<<":"<<x<<"]"<<"  ";
#define deb2(x,y) cout<<"["#x<<":"<<x<<" "#y<<":"<<y<<"]";
#define ff first
#define ss second
#define eb emplace_back
#define pb push_back
#define all(v) v.begin(),v.end()
#define endl ("\n")
typedef tree<ll int ,null_type,less<ll int> ,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//  *(set_name.find_by_order(k))    set_name.order_of_key(k)


 
int main (){
	clock_t t1, t2;
    t1 = clock();
	#ifndef ONLINE_JUDGE
	freopen("input.txt","r",stdin);
	freopen("output.txt","w",stdout);
	freopen("error.txt","w",stderr);
	#endif

    cheetah;
    cout<<fixed;
    cout.precision(10);
    int t = 1;
    // cin>>t;

    while(t--){
	    	ll int n,d;cin>>n>>d;
	    	ll int money = 0;
	    	ll int ans = 0;
	    	for(int i = 0;i<n;i++){
	    		ll int x;cin>>x;
	    		if(x==0){
	    			ans += (money<0)?1:0;
	    			ll int temp = 0;
	    			ll int temp1 = 0;
	    			int j;
	    			for(j = i+1;j<n;j++){
	    				int x1;cin>>x1;
	    				if(x1==0)
	    					break;
	    				if(x1<0){
	    					temp -= x1;
	    				}
	    				else{
	    					temp += x1;
	    				}
	    				temp1 = max(temp1,temp);
	    			}
	    			if(j==n){
	    				if(temp1>d){
	    					ans = -1;
	    				}
	    				break;
	    			}
	    			i = j-1;
	    			money = (d-temp1);
	    			continue;
	    		}
	    		money += x;
	    		if(money>d){
	    			ans = -1;
	    			break;
	    		}
	    	}
	    	cout<<ans<<endl;

    }


	


    t2 = clock(); 
    #ifndef ONLINE_JUDGE	
	cerr << "time taken : " << (t2 - t1) / (long double)CLOCKS_PER_SEC<<" seconds";
    #endif
  return 0;
}



