Return groups using the formula
return ( C [ 1 ] * C [ 2 ] + C [ 0 ] * ( C [ 0 ] - 1 ) / 2 + C [ 0 ] * ( C [ 0 ] - 1 ) * ( C [ 0 ] - 2 ) / 6 + C [ 1 ] * ( C [ 1 ] - 1 ) * ( C [ 1 ] - 2 ) / 6 + C [ 2 ] * ( C [ 2 ] - 1 ) * ( C [ 2 ] - 2 ) / 6 + C [ 0 ] * C [ 1 ] * C [ 2 ] ) NEW_LINE