balanced parenthesis using stack in C

this C program checks whether brackets are balanced or not in an string

Data Structures/stack/balanced parenthesis using stack in C

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+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#define size 100
+
+struct node
+{
+    char data;
+    struct node* link;
+};
+int c=0;
+struct node * head;
+
+void push(char x)
+{
+struct    node*p,*temp;
+    temp=(struct node*)malloc(sizeof(struct node));
+    temp->data=x;
+    if(head==NULL)
+    {
+        head=temp;
+        p=head;
+        p->link=NULL;
+        c++;
+    }
+    else
+    {
+        temp->link=p;
+        p=temp;
+        head=p;
+        c++;
+    }
+    
+}
+char pop(void)
+{
+    char x;
+    struct node*p=head;
+    x=p->data;
+    head=p->link;
+    free(p);
+    c--;
+    return x;
+    
+}
+
+int isBalanced(char *s) {   //{[()]}
+    int i=0;char x;
+ while(s[i]!='\0')
+ {
+     if(s[i]=='{'||s[i]=='('||s[i]=='[')
+         push(s[i]);
+        else 
+        {
+            if(c<=0)
+                return 0;
+        
+            
+               x=pop();
+                if( x=='{'&&s[i]!='}')
+                    return 0;
+                if(x=='['&&s[i]!=']')
+                    return 0;
+                if(x=='('&&s[i]!=')')
+                    return 0 ;
+        }i++;       
+    }
+      if(c==0)
+          return 1;
+        else
+            return 0;
+}
+
+int main() {
+    int t;
+    scanf("%d",&t);
+    for(int a0 = 0; a0 < t; a0++){
+        char s[size];
+int result;
+        scanf("%s",s);
+        result = isBalanced(s);
+if(result==1)
+printf("\nYES");
+else       
+ printf("\nNO");
+		
+    }
+    return 0;
+}