131ms

#include <iostream>
using namespace std;

const int N = 1e5 + 10;
int a[N];
int mid, n, q;

void search(int x) // 先找起点，后找终点
{
    int l = 0, r = n - 1, ans1, ans2;

    while (l < r)
    {
        mid = l + r >> 1;
        if (a[mid] >= x) r = mid;
        else l = mid + 1;
    }

    ans1 = l;

    l = 0, r = n - 1;

    while (l < r)
    {
        mid = (l + r + 1) >> 1;
        if (a[mid] <= x) l = mid;
        else r = mid - 1;
    }

    ans2 = r;

    if (ans1 > ans2 || a[ans1] != x || a[ans2] != x) 
        printf("%d %d\n", -1, -1);
    else printf("%d %d\n", ans1, ans2);
}


int main()
{
    int k;
    scanf("%d%d", &n, &q);

    for (int i = 0; i < n; i ++ )
        scanf("%d", &a[i]);

    while (q-- )
    {
        cin >> k;
        search(k);
    }

    return 0;
}