Razlika datuma (S)

// dragutinmarjanovic
#include <iostream>
using namespace std;

bool prestupna (int a)
{
     if ((a%4==0 && a%100!=0)||(a%400==0))
     return true;
     else return false;
}

long long br_dana(int mg, int d, int m, int g)
{
     long long s = 0;

     for (int i=mg; i<g; i++)
         if (prestupna(i)==true)
            s = s + 366;
         else
            s = s + 365;

     for (int i=1; i<m; i++)
     switch(i)
     {
              case 1: case 3: case 5: case 7: case 8: case 10: case 12: s = s + 31; break;
              case 4: case 6: case 9: case 11: s = s + 30; break;
              case 2:
                   if (prestupna(g)==true)
                      s = s + 29;
                   else
                      s = s + 28;
              break;
     }

     s = s + d;

     return s;
}

bool provjera_datuma (int d, int m, int g)
{
     bool p = true;

     if (d<1 || m<1 || m>12)
     p = false;

     switch(m)
     {
              case 1: case 3: case 5: case 7: case 8: case 10: case 12: if (d>31) p = false; break;
              case 4: case 6: case 9: case 11: if (d>30) p = false; break;
              case 2:
                   if (prestupna(g)==true) {if (d>29) p = false;}
                   else {if (d>28) p = false;}
              break;
     }

     return p;
}

main()
{
      int d1, d2, m1, m2, g1, g2, mg;

      cin >> d1 >> m1 >> g1;
      cin >> d2 >> m2 >> g2;

      if (provjera_datuma(d1, m1, g1)==true && provjera_datuma(d2, m2, g2)==true)
      {
          if (g1<g2)
          mg = g1;
          else mg = g2;
          if (br_dana(mg, d1, m1, g1) - br_dana(mg, d2, m2, g2) >= 0)
              cout << br_dana(mg, d1, m1, g1) - br_dana(mg, d2, m2, g2) << endl;
          else
              cout << br_dana(mg, d2, m2, g2) - br_dana(mg, d1, m1, g1) << endl;
      }
      else cout << "Ilegalan datum!" << endl;

      system ("PAUSE");
}