Given two strings count the number of unique characters

Given two strings count the number of unique characters

Input:

coderegister
codebuilders

Output:

8

Implementation:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(void) {
 char *s,*v;
 int i;
 int hash[26],count=0;
 memset(hash,0,sizeof(hash));
 s=(char*)malloc(sizeof(char)*1000);
 v=(char*)malloc(sizeof(char)*1000);
 scanf("%s",s);
 scanf("%s",v);
 i=0;
 while(*(s+i) || *(v+i))
 {
  hash[*(s+i)-'a']++;
  hash[*(v+i)-'a']++;
  i++;
 }
 i=0;
 while(i<26)
 {
  hash[i]%=2;
  if(hash[i]!=0)
   count++;
  i++;
 }
 printf("%d",count);
 return 0;
}