#include<iostream>
using namespace std;
int main(){
int h,w,s;
char c;
cin>>h>>w>>c>>s;
for(int i=1;i<=w;++i)cout<<c;
cout<<endl;
for(int i=2;i<=h-1;++i){
cout<<c;
for(int j=2;j<=w-1;j++){
if(s==0)cout<<" ";
else cout<<c;
}
cout<<c<<endl;
}
for(int i=1;i<=w;++i)cout<<c;
cout<<endl;
return 0;
}