#include <iostream>

int main(){
    int n, k, p;
    std::cin >> n >> k >> p;
    int cont = 100 * (1 + n - k) + (4 + n) * p, back = 100 * (2 + n - k) + (4 + n) * (100 - p), rest = 100 * (4 + n);
    if (cont < back && cont < rest) std::cout << "c" << std::endl;
    else if (back < rest) std::cout << "b" << std::endl;
    else std::cout << "r" << std::endl;
    return 0;
}