345
3
#include<iostream> using namespace std; int func(int n) { int s=0; int tmp; while(n) { tmp=n%10; s+=tmp; n=n/10; } return s; } int main() { int i=0,s=0,n; cin>>n; s=s+func(n); while(s>9) { s=func(s); } cout<<s<<endl; return 0; }