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

/*
___ is a raging sadist.
*/
//Destroy all WA at test 2
// Stay cool
// Pass the 4th wall..

#include "bits/stdc++.h"
#define fastio()                  \
    ios_base::sync_with_stdio(0); \
    cin.tie(0);                   \
    cout.tie(0)
#define pb push_back
#define show(x) cout << (#x) << " : " << x << endl;
#define ll long long
#define ld long double
#define pow power
#define mp make_pair
#define ff first
#define ss second
#define pii pair<ll, ll>
#define sq(x) ((x) * (x))
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define siz(a) int((a).size())
#define For(i,a,b) for(int (i)=(a);(i) < (b); ++(i))
#define endl "\n"
#define pi 3.14159265
const ll mod = 1000 * 1000 * 1000 + 7;
const ll mod1 = 998244353;
const ll INF     = 1ll*1000*1000*1000*1000*1000*1000 + 7; 
using namespace std;

ll power(ll x, ll y) 
{ 
   ll res = 1;      
  
   
    while (y > 0) 
    { 
       
        if (y & 1) 
            res = (long long)(res*x); 
  

        y = y>>1; 

        if (x<=100000000)
        x = (long long)(x*x);

        //cout<<x<<'\n'; 
    } 
    return res; 
} 






int main()
{

#ifndef ONLINE_JUDGE    
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif

fastio();

    
    ll n,d;
    cin>>n>>d;

    ll dep[n]; ll sufm[n]={};

    For(i,0,n)
    cin>>dep[i];

    ll sum=0;

    For(i,0,n)
    {
        sum+=dep[i];
        if (sum>d)
        {
            cout<<-1;
            return 0;
        }
        sufm[i]=-INF;
    }


    ll ans = dep[n-1], min_sum = 0; sum=0;

    for (int r = n-1; r >= 0; --r) {
        sum += dep[r];
        ans = max(ans, sum - min_sum);
        min_sum = min(min_sum, sum);
        sufm[r]=ans;
    }

    //cout<<sufm[4]<<endl;

    ll fin=0; sum=0;

    for(int i=0;i<n;i++)
    {
        sum+=dep[i];

        if (sum>d)
        {
            cout<<-1;
            return 0;
        }

        if (i==n-1 and dep[i]==0 and sum<0)
        {
            fin+=1;
            break;
        }

        if (dep[i]==0 and sum<0)
        {
            ll cur=d-(sufm[i+1]+sum);
            if (cur<=0)
            {
                cout<<-1;
                return 0;
            }
            sum+=cur;
            fin+=1;
        }
    }


    cout<<fin;



return 0;
}

// check all product based operations for integer overflow