Ответ:

#include <iostream>

int main()

{

int n,n1,k,k1;

std::cout << "n = ";

std::cin >> n;

std::cout << "k = ";

std::cin >> k;

n1 = n;

k1 = 1;

while ((n1 /= 10) > 0) k1++;

n1 = n;

while (k1-- != k) n1 /= 10;

k1 = n1%10;

while ((n1 /= 10) > 0) k1 += n1 % 10;

std::cout << "Result = " << k1;

   return 0;

}