P18777: Dia de la setmana

#include <iostream>
using namespace std;


//Pre: Llegeix una data
//Post: Sabem el dia de la setmana
string dia_de_la_setmana(int d, int m, int a) {
    int c, y, f;
    m = m - 2;
    if (m <= 0) {
        m = m + 12;
        --a;
    }
    c = a/100;
    y = a%100;
    f = ((2.6 * m) - 0.2);
    f= f + d + y + (y / 4) + (c / 4) - (2 * c);
    while (f < 0) f = f + 7;
    f = f%7;
    if (f == 0) return "diumenge";
    else if (f == 1) return "dilluns";
    else if (f == 2) return "dimarts";
    else if (f == 3) return "dimecres";
    else if (f == 4) return "dijous";
    else if (f == 5) return "divendres";
    else return "dissabte";
}

int main() {
    int d, m, a;
    cin >> d >> m >> a;
    cout << dia_de_la_setmana(d, m, a) << endl;
}