#include<iostream> #include<cstdio> using namespace std; int main(){ int n; cin >> n; int xz[101] {0}; int p1,p2; for( int i = 1;i <= n; i++){ cin >> p1 ; xz[p1]++; xz[p2]++; } int bz =1; for( int i = 1;i <= n; i++){ if( xz[i] == 1 ){ bz = i; } } cout<<bz<<endl; return 0; }