#include<iostream> #include<cstdio> #include<algorithm> using namespace std; int maxn=1000; int main(){ int n; while(scanf("%d",&n)!=EOF){ int arr[maxn]; if(n==1){ scanf("%d",&arr[0]); printf("%d\n",arr[0]); printf("-1"); break; } else{ for(int i=0;i<n;++i){ scanf("%d",&...