#include<bits/stdc++.h> using namespace std; int ax[2001]; double n,d=10,c; double x,m=100; int main(){ cin>>n; for(int i=0;i<=n-1;i++){ cin>>ax[i]; } cin>>c; for(int i=0;i<=n-1;i++){ if(ax[i]==c){ m=10; cout<<i+1<<" "; break; } } for(int i=n-1;i>=0;i--){ if(ax[i]==c){ m=10; cout<<i+1<<" "; break; } } if(m==100){ cout<<-1; } return 0; }