#include #define REP(i, n) for(int i = 0; i < n; i++) #define REPR(i, n) for(int i = n; i >= 0; i--) #define FOR(i, m, n) for(int i = m; i < n; i++) #define INF 2e9 #define ALL(v) (v).begin(), (v).end() using namespace std; typedef long long ll; int GCD(int a,int b){return b?GCD(b,a%b):a;} int LCM(int a,int b){return (a*b)/GCD(a,b);} int abs(int x){return x>0?x:-x;} //const int dx[] = {1, 0, -1, 0, 1, -1, -1, 1}; //const int dy[] = {0, 1, 0, -1, 1, 1, -1, -1}; int main() { bool a[10] = {}; REP(i, 9){ int b; cin >> b; a[b-1] = 1; } REP(i, 10){ if (a[i] == 0) cout << i+1 << endl; } }