#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<n; ++i)
#define repl(i,m,n) for(ll i=m; i<n; ++i)

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

    cout << S;
    rep(i, 0, N) cout << "_" << T;
    cout << endl;

    return 0;
}