#include<bits/stdc++.h> using namespace std; int main(){ int n,a,c; char b; cin>>n>>a>>b>>c; for(int i=1;i<=n;i++){ for(int j=1;j<=a;j++){ if(i==1||i==n||j==1||j==a) cout<<b; else cout<<b; } cout<<endl; } return 0; }