#include<bits/stdc++.h>
using namespace std;
long long c[100002],sum[100002];
int main(){
    int n;
    long long p;
    scanf("%d %lld",&n,&p);
    for(int i=1;i<=n;i++)
    {
        scanf("%lld",&c[i]);
        sum[i]=sum[i-1]+c[i];
    }
    c[n+1]=p+1;
    int l=1,r=n+1,ans=-1;
    auto check=[&](const int &pos)->bool
    {
        return (__int128)(c[pos]-1)*pos+sum[pos-1]>p;
    };
    while(l<=r)
    {
        int mid=(l+r)>>1;
        if(check(mid))
        {
            ans=mid-1;
            r=mid-1;
        }
        else
            l=mid+1;
    }
    printf("%d\n",ans);
    
    return 0;
}