#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
  long long n,q;cin>>n>>q;
  vector<long long> A(n),B(n+1),C(n+1);
  for(int i = 0; n > i; i++){
    cin>>A[i];
    B[i+1] = B[i]+A[i];
    C[i+1] = C[i]+B[i+1];
  }
  for(int i = 0; q > i; i++){
    long long x;cin>>x;
    if(C[n] < x){
      cout << -1 << endl;
      continue;
    }
    long long ans = 0;
    long long z = upper_bound(C.begin(),C.end(), x)-C.begin()-1;
    ans += z*(z+1)/2;
    x -= C[z];
    long long y = lower_bound(B.begin(),B.end(), x)-B.begin();
    ans += y;
    cout << ans << endl;
  }
}