Can someone suggest what's wrong in logic

/ package codechef; // don't place package name! /

import java.util.; import java.lang.; import java.io.*; import java.lang.Math;

/ Name of the class has to be "Main" only if the class is public. / class Codechef { public static void main (String[] args) throws java.lang.Exception { // your code goes herene int sum=0; Scanner sc=new Scanner(System.in); int t=sc.nextInt(); int a[]=new int[26]; while(t-->0){ sum=0; String s=sc.next(); s=s.toLowerCase(); int n=s.length(); for(int m=0;m<26;m++) a[m] = 0; for(int i=0;i<n;i++) { a[s.charAt(i)-'a']++; }

        for(int j=0;j<26;j++)
        {
            if(a[j]==0)
            continue;
            sum=(int)(sum+Math.ceil((a[j])/2.0));
        }
        System.out.println(sum);
    }
}

}