Function to multiply matrix .
static void multiply ( int [ , ] F , int [ , ] M ) { int x = F [ 0 , 0 ] * M [ 0 , 0 ] + F [ 0 , 1 ] * M [ 1 , 0 ] ; int y = F [ 0 , 0 ] * M [ 0 , 1 ] + F [ 0 , 1 ] * M [ 1 , 1 ] ; int z = F [ 1 , 0 ] * M [ 0 , 0 ] + F [ 1 , 1 ] * M [ 1 , 0 ] ; int w = F [ 1 , 0 ] * M [ 0 , 1 ] + F [ 1 , 1 ] * M [ 1 , 1 ] ; F [ 0 , 0 ] = x ; F [ 0 , 1 ] = y ; F [ 1 , 0 ] = z ; F [ 1 , 1 ] = w ; }