simple one

#include<iostream>
using namespace std;
int n,x,a[1000005];
int main(){
cin>>n;
for(int i=1;i<=n;i++){
cin>>a[i];
}
cin>>x;
int mid,l=1,r=n;
while(l<=r){
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";
return 0;
}