#include<iostream>
#include<vector>

using namespace std;

int main( void )
{
    string S, T;
    cin >> S >> T;
    int N;
    cin >> N;

    cout << S;
    for( int i = 0; i < N; i++ )
    {
        cout << '_' << T;
    }
    cout << endl;

    return 0;
}