#include <bits/stdc++.h> using namespace std; #define rep(i,n) for(int i=0;i<(n);i++) #define rep_lr(i,l,r) for(int i=(l);i<(r);i++) #define all(x) (x).begin(),(x).end() #define V vector typedef V<int> vi; typedef V<vi> vvi; typedef long long ll; typedef pair<ll, ll> P; typedef tuple<int, int, int> T; constexpr int INF = INT_MAX >> 1; constexpr ll LINF = 5000000000000000LL; constexpr int MOD = 1000000007; int ten(int i) { int ret = 0; while (i) { ret += i % 10; i /= 10; } return ret; } int main() { int n; cin >> n; rep(i, 99) { n = ten(n); } cout << n << endl; }