PAT 1037 在霍格沃茨找零钱 （20 分）

#include<iostream>
using namespace std;
int main()
{
   int a[3], b[3], c[3];
   char ch;
   cin >> a[0] >>ch>> a[1] >>ch>> a[2] >> b[0] >>ch>> b[1] >>ch>> b[2];
   int ka, kb, res;
   ka = (a[0] * 17 + a[1]) * 29 + a[2];
   kb = (b[0] * 17 + b[1]) * 29 + b[2];
   res = kb - ka;
   if (res < 0) {
       res = -res;
       ch = '-';
   }
   c[0] = res / 29 / 17;
   c[1] = res / 29 % 17;
   c[2] = res % 29;
   if (ch == '-')
       cout << ch;
   cout << c[0] << "." << c[1] << "." << c[2];
   return 0;
}