#include "iostream.h"

int equiv(int i, int j)
{
    if ((i % 4) == (j % 4))
	{
		return -1;
	}
	else
	{
		return 0;
	}
}

void main()
{
    //program d7r11
    //driver for routine eclazz
    int i,j,n = 15;
    int nf[16],nflag[16], nsav[16];
    eclazz(nf, n);
	cout.setf(ios::right);
    for (i = 1; i<=n; i++)
	{
        nflag[i] = 1;
    }
    cout<<endl;
    cout<<"Numbers from 1-15 divided according to"<<endl;
    cout<<endl;
    cout<<"their value modulo 4:"<<endl;
    cout<<endl;
    int k,nclass,lclas = 0;
    for (i = 1; i<=n; i++)
	{
        nclass = nf[i];
        if (nflag[nclass] != 0)
		{
            nflag[nclass] = 0;
            lclas = lclas + 1;
            k = 0;
            for (j = 1; j<=n; j++)
			{
                if (nf[j] == nf[i])
				{
                    k = k + 1;
                    nsav[k] = j;
                }
            }
            cout<<"Class"<<lclas<<":"<<" ";   
            for (j = 1; j<=k; j++)
			{
				cout.width(4);
                cout<<nsav[j];
            }
            cout<<endl;
        }
    }
}