#include <iostream>
#include <iomanip>
#include <string>

using namespace std;

const string DAYS = "UMTWRFS";

class Month
{
private:
    int numDays;
    int startDOW;
public:
    Month(int days, char day1){this->numDays = days; this->startDOW = string("UMTWRFS").find(day1);};
    friend ostream & operator<<(ostream & out, Month m){
        cout << "Su Mo Tu We Th Fr Sa" << endl;
        int prints = 7;
        for (int i = 0;i < m.startDOW;i++, prints++) cout << "   ";
        for (int day = 1;day <= m.numDays; day++, prints++){
            if (!(prints % 7)) cout << endl;
            cout << setw(2) << day;
            cout << ' ';
        }
    }
};

int main()
{
    int year, month;
    char startDay;
    do {
        cout << "Please enter the year: ";
        cin >> year;
    } while ((year < 1) || (year > 9999));
    do {
        cout << "Please enter the month (1-12): ";
        cin >> month;
    } while ((month < 1) || (month > 12));
    do {
        cout << "Please enter the day of week that the year begins with (U,M,T,W,R,F,S): ";
        cin >> startDay;
    } while (DAYS.find(startDay) == string::npos);
    int lengths[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    int totalDays = 0;
    for (int i = 0; i < month; i++) totalDays += lengths[i];
    if ((month > 2) && (!(year % 4) || (!(year % 100) && !(year % 400)))) totalDays++; // leap year, and yes, there probably are too many parens
    Month cal(lengths[month], ((DAYS.find(startDay)+totalDays) % 7)+1); // not 100% sure abt the math for the second arg
    cout << "\n\n\n" << cal << endl; // original string to make it look nice.
    return 0;
}