uva350 PseudoRandom Numbers

#include<stdio.h>
int main()
{
    int Z, I, M, L, i = 1;
    while(scanf("%d%d%d%d",&Z,&I,&M,&L) && (Z||I||M||L))
    {
        int f[10002] = {0}, k = -1;
        do
        {
            k++;
            L = ((Z%M)*(L%M)+I)%M;
            f[L]++;
        }while(f[L]==1);
        printf("Case %d: %d\n",i++,k);
    }
    return 0;
}