include <bits/stdc++.h>

using namespace std; int main() {

int n,m,k;
char ch;
cin>>n>>m>>ch>>k;
for(int i=1; i<=n; i++)
{
	for(int j=1; j<=m; j++)
	{
		if(k==1||j==1||j==m||i==1||i==n)
			cout<<ch;
		else
			cout<<" ";
	}
	cout<<endl;
}
return 0;

}