sohanhphuc

#include <stdio.h>

int countDigits(int n)
{
        int count = 0;
        while (n != 0)
        {
                n /= 10;
                count++;
        }

        return count;
}

int happyNumber(int n)
{

        int digits = countDigits(n);
        int left = 0, right = 0, i;

        for (i = 0; i < digits / 2; i++)
        {
                right += n % 10;
                n /= 10;
        }

        if (digits % 2 == 1)
        n /= 10;

        for (i = 0; i < digits / 2; i++)
        {
                left += n % 10;
                n /= 10;
        }

        if (left == right)
          return 1;
        return 0;
}

main()
{
        int n;
        printf("n = ");
        scanf("%d", &n);

        for (int i = 0; i < n; i++)
                if (happyNumber(i * i)) printf("\n%d %d", i, i * i);

        return 0;
}