• Source 
    1. #include <iostream> 
    2. #include <string.h> 
    3. #include <stdlib.h> 
    4. using namespace std;
    5.  
    6. int main()
    7. {
    8.  char s[5];
    9.  cin >> s;
    10.  if (strlen(s) != 5 || (int)s[0]<'A' || (int)s[0]>'H' || (int)s[3]<'A' || (int)s[3]>'H' ||
    11.  int(s[1])>'8' || int(s[1])<'1' || int(s[4])>'8' || int(s[4])<'1' || int(s[2]) != '-')
    12.  {
    13.  cout << "ERROR";
    14.  return 0;
    15.  }
    16.  if ((abs((int)(s[0] - s[3])) == 1 && abs((int)(s[1] - s[4])) == 2) ||
    17.   (abs((int)(s[0] - s[3])) == 2 && abs((int)(s[1] - s[4])) == 1))
    18.  cout << "YES";
    19.  else cout << "NO";
    20.  return 0;
    21. }