这

#include <bits/stdc++.h>
using namespace std;
int n,mid,a[10001],mx=0,x,rig,lef;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
		
	}
	
	cin>>x;
	rig=n,lef=1;
	
	
	while(lef<=rig)
	{
		mid=(rig+lef)/2;
		if(a[mid]==x)
		{
			cout<<mid<<endl;
			return 0;
		}
		else if(a[mid]<x)
		{
			lef=mid+1;
		}
		else if(a[mid]>x)
		{
			rig=mid-1;
		}
	}
	
	cout<<"-1"<<endl;
	return 0;

}