#include<bits/stdc++.h>
using namespace std;
int main(){
int x=0,y=0,k=0;char m;
cin>>x>>y>>m>>k;
for(int i=1;i<=y;i++){
for(int j=1;j<=x;j++){
		if(j==1||j==x||i==1||i==y)cout<<m;
		else if(k==0)cout<<" ";
		else cout<<m;
	}
	cout<<endl;
}
return 0;
}