#include<bits/stdc++.h> using namespace std; int main(){ int n,m,a[100]; cin>>n; for(int i=0;i<n;i++){ cin>>a[i]; } cin>>m; int l=0,r=n-1,mid; while(l<=r){ mid=(r-l)/2; if(a[mid]==m){ cout<<mid+1; return 0; } if(mid<m){ l=mid+1; } else{ r=mid-1; } } cout<<"-1"; return 0; }