Before:

if( isLatitude )  // reading in latitude
{
   do {
      cout << "Enter the minutes latitude" << endl;
      cin >> minutes;
   } while( minutes < 0 || minutes >= 60 );
}
else // reading in longitude
{
   do {
      cout << "Enter the minutes longitude" << endl;
      cin >> minutes;
   } while( minutes < 0 || minutes >= 60 );
}