二分第一个点wa

#include <cstdio>

int num[1000010], n;
int check(int x)
{
    int l = 1, r = n, mid;
    while(l <= r)
    {
        mid = (l + r) / 2;
        if(num[mid] == x)
        {
            if(num[mid - 1] == x)
                r = mid - 1;   //找第一个
            else
                return mid;            
        }
        else if(num[mid] > x)
            r = mid - 1;
        else
            l = mid + 1;
    }
    return -1;
}
int main()
{
    int m, tem;
    scanf("%d %d", &n, &m);
    for(int i = 1; i <= n; i++)
        scanf("%d", &num[i]);
    for(int i = 1; i <= m; i++)
    {
        scanf("%d", &tem);
        printf("%d ", check(tem));
    }
    return 0;
}