#include <iostream>
#include <string>

int main()
{
    std::string s, t;
    int n;
    std::cin >> s >> t >> n;
    std::cout << s;
    for(int i = 0; i < n; i++)
    {
        std::cout << "_" << t;
    }
    std::cout << std::endl;
    return 0;
}