为啥RE 蒟蒻求调 互关

#include<bits/stdc++.h>
using namespace std;
const int N = 1e5+10;
int a[N], q[N],mid;
int n, m; //数字个数和询问次数
int bin_search(int x) {
    int l = 1, r = n;
    while (l < r) {
        mid = l + (r - l) / 2;
        if (x > a[mid]) {
            l = mid + 1;
        } else {
            r = mid;
        }
    }
    if (a[l] == x) {
        return l;
    } else {
        return -1;
    }
}
int main() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    for (int j = 1; j <= m; j++) {
        cin >> q[j];
        cout << bin_search(q[j]) << " ";
    }
    return 0;
}