#include <stdio.h>
int top =-1;
int n,i=0;
void push ()
{
    int stack [n]
    if (top == -1)
    {
        for(top= -1; top<n;top++)
        {
            printf("%d",stack[top]);
        }
    }
    int n;
    if(n < 0)
    {
        printf("Invalid input");
    }
    else
    {
        
            push();
        
    }
}