import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int q = sc.nextInt();
        int[] sums = new int[n];
        long[] sumsums = new long[n];
        sums[0] = sc.nextInt();
        sumsums[0] = sums[0];
        for (int i = 1; i < n; i++) {
            sums[i] = sums[i - 1] + sc.nextInt();
            sumsums[i] = sumsums[i - 1] + sums[i];
        }
        StringBuilder sb = new StringBuilder();
        while (q-- > 0) {
            int x = sc.nextInt();
            if (x > sumsums[n - 1]) {
                sb.append("-1\n");
                continue;
            }
            int left1 = -1;
            int right1 = n - 1;
            while (right1 - left1 > 1) {
                int m = (left1 + right1) / 2;
                if (sumsums[m] < x) {
                    left1 = m;
                } else {
                    right1 = m;
                }
            }
            long y;
            if (right1 > 0) {
                y = x - sumsums[right1 - 1];
            } else {
                y = x;
            }
            int left2 = -1;
            int right2 = right1;
            while (right2 - left2 > 1) {
                int m = (left2 + right2) / 2;
                if (sums[m] < y) {
                    left2 = m;
                } else {
                    right2 = m;
                }
            }
            sb.append((right1 + 1L) * right1 / 2 + right2 + 1).append("\n");
        }
        System.out.print(sb);
    }
}
    
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}