#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, q;
  cin >> n >> q;
  vector<int> a(n);
  rep(i, n) cin >> a[i];
  vector<int> b;
  rep(i, n) {
    for (int x = 1; x <= a[i]; ++x) b.push_back(x);
  }
  vector<ll> sum(b.size() + 1);
  rep(i, b.size()) sum[i + 1] = sum[i] + b[i];
  while (q--) {
    ll s;
    cin >> s;
    auto it = lower_bound(sum.begin(), sum.end(), s);
    if (it == sum.end()) {
      cout << -1 << '\n';
    }
    else {
      cout << it - sum.begin() << '\n';
    }
  }
  return 0;
}