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/* A happy number is a number whose sum of digits is calculated until the sum is a single digit,
and this sum turns out to be 1 */
#include <iostream>
using namespace std;
int main()
{
int n, k, s = 0, d;
cout << "Enter a number:";
cin >> n;
s = 0;
k = n;
while (k > 9)
{
while (k != 0)
{
d = k % 10;
s += d;
k /= 10;
}
k = s;
s = 0;
}
if (k == 1)
cout << n << " is a happy number" << endl;
else
cout << n << " is not a happy number" << endl;
return 0;
}