#include<bits/stdc++.h> using namespace std; int main() { int n; cin >> n; int b[101] = {0}; for (int i = 0; i < 101; i++) { int x ; cin >> x; b[x]++; } int max = 1; for (int i = 2; i <= 101; i++) { if (a[i]%2!=0) { cout<<i; } } cout << max; return 0; }