1519

#include <iostream>#include <string>

int main(){std::string in;while(std::getline(std::cin, in)){int sum = 0;for(std::string::size_type i = 0; i < in.length(); ++i){sum += in[i] - '0';}if(sum != 0){int ret = sum % 9;if(0 == ret){ret = 9;}std::cout << ret << std::endl;}else{break;}}return 0;}