#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int N,Q; cin >> N >> Q;
    vector<ll> A(N);
    rep(i,N) cin >> A[i];

    vector<ll> B;
    rep(i,N) for(int x = 1; x <= A[i]; x++) B.push_back(x);
    N = B.size();
    vector<ll> B_sum(N + 1, 0);
    rep(i,N) B_sum[i + 1] += B_sum[i] + B[i];

    rep(_,Q) {
        ll S; cin >> S;
        auto it = lower_bound(B_sum.begin(), B_sum.end(), S);
        if(it == B_sum.end()) {
            cout << -1 << "\n";
        } else {
            cout << it - B_sum.begin() << "\n";
        }
    }
}