문자열 역순 뒤집기

#include <stdio.h>
#define MAX_SIZE 20
int stack[MAX_SIZE];
int top =-1;
int overflow = 0, underflow = 0;
 
int push(char x)
{
	top+=1;
	stack[top]=x;
 
	return(0);
} 
 
int pop()
{
 	printf("%c",stack[top]);
 	top--;
	return(0);
}
 
int main()
{
	char x[9];
	while(scanf("%c",&x)!='\n')
	{
	      push(*x);
	}
	while(top<=0)
	{
		pop();
	}
	return(0);
}