#define _USE_MATH_DEFINES
#include<iostream>
#include<vector>
#include<algorithm>
#include<cmath>
#include<string>
#include<iomanip>
#include<numeric>
#include<queue>
#include<deque>
#include<stack>
#include<set>
#include<map>
#include<random>
#include<bitset>
#include<cassert>
#include<complex>
#include<fstream>
#include<cstdlib>
#include<functional>
#include<array>
using namespace std;
typedef long long ll;
const int mod=998244353;
const int dx[]={1,0,0,-1},dy[]={0,1,-1,0};
ll sum[100001];
int main(){
	int n,q,a,s;
	cin>>n>>q;
	vector<int>b;
	for(int i=0;i<n;i++){
		cin>>a;
		for(int j=1;j<=a;j++)
			b.push_back(j);
	}
	for(int i=0;i<b.size();i++)
		sum[i+1]=sum[i]+b[i];
	while(cin>>s)
		cout<<(sum[b.size()]<s?-1:lower_bound(sum,sum+b.size(),s)-sum)<<endl;
}