#include<iostream>
#include<cmath>
using namespace std;
int main(){
	long long a=0,b=0,d=0;
	char c=0;
	cin>>a>>b>>c>>d;
	if(d==0){
		for(int i=1;i<=a;++i){
			for(int j=1;j<=b;++j){
				if(i==1||i==a||j==1||j==b){
					cout<<c;
				}else cout<<' ';
			}
			cout<<endl;
		}
	}else if(d!=0){
		    for(int i=1;i<=b;++i){
			    for(int j=1;j<=b;++j){
					cout<<c;
			}
			cout<<endl;
		}
	}
}