C program to check if an input string is a palindrome

#include<stdio.h>
#include <ctype.h>
#include <string.h>

int main()
{
   char str[100];
   int i, size, counter=0;

   printf("Enter a string:");
   gets(str);

   size=strlen(str);
   for(i=0;i<size;i++){
    if (str[i]!=str[size-i-1]){
        counter=1;
        break;
    }
   }
   if(counter==0)
   {
       printf("Its a palindrme");
   }
   else{
    printf("Not a palindrome");

   }
 return 0;
}