#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;

int main(){
	
	const string days[] {
		"Monday",
		"Tuesday",
		"Wednesday",
		"Thursday",
		"Friday",
		"Saturday",
		"Sunday"
	};
	int cday {0};
	cout << "Please enter the current day of the week as a number where Monday is 0 and Sunday is 6.\n";
	cin >> cday;
	if (!cin) {
		cerr << "Sorry, that is not a valid number.\n";
		return EXIT_FAILURE;
	}
	if (cday > 6){
		cerr << "Sorry, that is not a valid number.\n";
		return EXIT_FAILURE;
	}
	if (cday < 0){
		cerr << "Sorry, that is not a valid number.\n";
		return EXIT_FAILURE;
	}
	
	int howmuch {0};
	cout << "How many days ahead are you looking ahead?\n";
	cin >> howmuch;
	if (!cin) {
		cerr << "Sorry, that was not a valid number.\n";
		return EXIT_FAILURE;
	}
	const int total {(cday + howmuch) % 7};
	const int weeks {(cday + howmuch) / 7};
	string nday {"days"};
	string nweek {"weeks"};
	if(total == 1){
		nday = "day";
	}
	if(weeks == 1){
		nweek = "week";
	}

	cout << "It is " << days[cday] << ".\n"
	     << "In " << howmuch << " " << nday << " it will be a " 
	     << days[total] << " " << weeks << " " << nweek << " from now.\n";
	return EXIT_SUCCESS;
}