#include using namespace std; #define fs first #define sc second #define pb push_back #define mp make_pair #define eb emplace_back #define ALL(A) A.begin(),A.end() #define RALL(A) A.rbegin(),A.rend() typedef long long LL; typedef pair P; 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; } template T gcd(T a,T b){return b?gcd(b,a%b):a;} const LL mod=1000000007; const LL LINF=1LL<<60; const int INF=1<<30; int dx[]={1,0,-1,0,1,-1,1,-1}; int dy[]={0,1,0,-1,1,-1,-1,1}; int main(){ LL n;cin >> n; for (int i = 0; i < 100; i++) { LL tn = n; string s = to_string(tn); LL p = 0; for (int j = 0; j < s.length(); j++) { p += s[j] - '0'; } n = p; } cout << n << endl; return 0; }