Balancing paranthesis in data structures

#include<stdio.h>

#include<conio.h>

#define MAX 50

struct stack

{

int a[MAX];

}s1;

int top=-1,i;

char s[MAX];

void main()

{

clrscr();

printf("\nEnter the expression:");

scanf("%s",&s);

for(i=0;s[i]!='\0';i++)

{

if(s[i]=='(')

{

top=top+1 ;

s1.a[top]=s[i];

}

else if(s[i]==')')

{

top=top-1;

}}

if(top==-1)

printf("\nBalanced Paranthesis");

else

printf("\nUnbalanced Paranthesis");

getch();

}