Helper function that multiplies 2 matrices F and M of size 2 * 2 , and puts the multiplication result back to F [ ] [ ]
void multiply ( long long F [ 2 ] [ 2 ] , long long M [ 2 ] [ 2 ] , long long m ) { long long x = ( ( F [ 0 ] [ 0 ] * M [ 0 ] [ 0 ] ) % m + ( F [ 0 ] [ 1 ] * M [ 1 ] [ 0 ] ) % m ) % m ; long long y = ( ( F [ 0 ] [ 0 ] * M [ 0 ] [ 1 ] ) % m + ( F [ 0 ] [ 1 ] * M [ 1 ] [ 1 ] ) % m ) % m ; long long z = ( ( F [ 1 ] [ 0 ] * M [ 0 ] [ 0 ] ) % m + ( F [ 1 ] [ 1 ] * M [ 1 ] [ 0 ] ) % m ) % m ; long long w = ( ( F [ 1 ] [ 0 ] * M [ 0 ] [ 1 ] ) % m + ( F [ 1 ] [ 1 ] * M [ 1 ] [ 1 ] ) % m ) % m ; F [ 0 ] [ 0 ] = x ; F [ 0 ] [ 1 ] = y ; F [ 1 ] [ 0 ] = z ; F [ 1 ] [ 1 ] = w ; }