#include <bits/stdc++.h>
using namespace std;
#define ll long long
ll s[100000];
ll Efcz(ll x,ll y,ll z){
	ll l=x,r=y,mid;
	while(l<=r){
		mid=(l+r)/2;
		if(s[mid]==z)return mid;
		else if(s[mid]>z)r=mid-1;
		else if(s[mid]<=z)l=mid+1;
	}
	return -1;
}
int main(){
	ll n,x;
	cin>>n>>x;
	for(ll i=0;i<n;i++){
		cin>>s[i];
	}
	ll ans=Efcz(0,n,x);
	if(ans==-1)cout<<"no";
	else cout<<ans+1;
	return 0;
}

为啥这么简单，在挑衅我的实力

@