#include<iostream>
#include<algorithm>
#include<stack>
#include<vector>

using namespace std;
using ll = long long;

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    string s,t;
    cin>>s>>t;
    int n;
    cin>>n;
    cout<<s;
    for(int i = 0;i<n;i++) cout<<'_'<<t;
    cout<<endl;
}