UVA350-水题

#include<iostream>

using namespace std;

int main()

{

	int c = 0;

	int Z, L, I, M;

	while (cin >> Z >> I >> M >> L)

	{

		c++;

		if(Z == L && L == I && I == M && M == 0)

		{

			return 0;

		}

		int i = 1;

		int K, P;

		I = I % M;

		Z = Z % M;

		K = L;

		L = P = (Z * L + I) % M;

		while (K != L)

		{

			L = (Z * L + I) % M;

			if(L == P)

				break;

			i++;

		}

		cout << "Case " << c << ": " << i << endl;

	}

	return 0;

}