~cpp 
#include <iostream>
using namespace std;

int main(){
	int year, month;
	int theFirstDay;
	char day[7][4] = {"SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT"};
	int numOfMonth[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
	
	cout << "Input Year : ";
	cin >> year;
	cout << "Input month : ";
	cin >> month;

	if ( year % 4 == 0 && ( year % 100 != 0 || year % 400 == 0 ) )
		numOfMonth[1] = 29;

	theFirstDay = ( --year * 365 + year / 4 - year / 100 + year / 400 + 1 ) % 7;

	for (int i = 1 ; i < month ; i++){
		theFirstDay = ( theFirstDay + numOfMonth[i - 1] ) % 7;
	}

	cout << "SUN\tMON\tTUE\tWED\tTHU\tFRI\tSAT" << endl;

	for (i = 0 ; i < theFirstDay ; i++)
		cout << "\t";
	for (i = 0 ; i < numOfMonth[month - 1] ; i++){
		if ( ( theFirstDay + i ) % 7 == 0 && i != 0 )
			cout << endl;
		cout << i + 1 << "\t";
	}
	cout << endl;

	return 0;
}