tj

#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,x,a[11000];
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i];
    }cin>>x;
    int l=1,r=n;
    while(l<=r){
        int mid=(l+r)/2;
        if(a[mid]==x){
            cout<<mid;
            return 0;
        }else if(a[mid]>x)r=mid-1;
        else l=mid+1;
    }cout<<-1;
}