#include #define rep(i,n) for (int i = 0; i < (n); ++i) #define printVec(v) printf("{"); for (const auto& i : v) { std::cout << i << ", "; } printf("}\n"); #define degreeToRadian(deg) (((deg)/360)*2*M_PI) #define radianTodegree(rad) (((rad)/2/M_PI)*360) template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } using namespace std; using P = pair; using ll = long long; const ll INF = 1LL<<60; const int MOD = 1e9 + 7; const int dx[4] = {1, 0, -1, 0}; const int dy[4] = {0, 1, 0, -1}; //cin.tie(0);ios::sync_with_stdio(false); //cout << fixed << setprecision(15) << y << endl; int main() { string s; cin >> s; rep (i, 100) { int x = 0; rep (j, s.size()) x += (s[j] - '0'); s = to_string(x); } cout << s << endl; return 0; }