3.

#include <iostream>
using namespace std;

void display (char ='*' , int = 4);


int main(){
int count;
cin>>count;

// invoke the function without param
display();

//invoke the function with one param
display('@');


// invoke the function with 2 param

display('#', count);
return 0;
}

void display (char ch , int count){

for(int i=1;i<=count;i++){
  cout<<ch;
}
cout<<endl;
}