bool isPrimef(int n){
    if (n == 1     ) return false;
    if (n <  4     ) return true;
    if (n %  2 == 0) return false;
    if (n <  9     ) return true;
    if (n %  3 == 0) return false;
    else{
        int r = std::sqrt(n);
        int f = 5;
        while (f <= r){

from math import *
 
def sumOfDigit(n):
    if n<10: return n
    sum = 0
    if n >0:
        sum += n%10
        n /= 10
    return sum