Getting WA in two cases 4 and 10. What's wrong with this code?

#include<cstdio>
#include<algorithm>
using namespace std;
 
int beg_bin(int a[], int n, int x)
{
    int l = 0, r = n-1;
    
    while(l<=r) {
        int mid = (l+r)/2;
        
        if(a[mid] <= x && a[mid+1] > x)
            return a[mid];
        
        else if(a[mid] < x) l = mid+1;
        
        else r = mid-1;
    }
}
 
int end_bin(int a[], int n, int x)
{