#include<iostream>

int main()
{
  double n;
  std::cout << "Enter a positive real number: ";
  do
  {
    std::cin >> n;
    if(n <= 0) std::cout<<"The number must be positive, enter again: ";
  }while(n <= 0);

  n *= 10000;
  int Integer = n;
  
  int i = 4;
  int sum = 0;
  while(i--)
  {
    sum += (Integer%10);
    Integer /= 10;
  }
  std::cout << "The sum of the first 4 digits is: " << sum;

  return 0;
}