#include <iostream>
#include <stdexcept>
using namespace std;
class Date{
    public:
        class Invalid{};// A class as exception
        Date(int y, int m,int d);
        Date():Date(0,1,1){}
        int year(){return y;}
        int month(){return m;}
        int day(){return d;}
    private:
        int y, m, d;
        bool is_valid();
};
Date::Date(int yy,int mm,int dd):y{yy},m{mm},d{dd}
{
    if(!is_valid()) throw Invalid{};
}
bool Date::is_valid(){
    if(m<1||m>12) return false;
    // skip other checkings.
    else return true;
}
void f(int m){
    try{
        Date date {2014,m,2};
        cout<<date.month()<<endl;
    }
    catch(Date::Invalid){
        throw invalid_argument("invalid date");
    }
}
int main(){
    int x=1;
    try{
        f(x);
        f(x+12);
        f(x+3);
    }
    catch(exception & e){
        cout<<e.what()<<endl;
    }
    f(x+2);
}