// O(log n)
public static long GetValueWithMod(long n, long mod)
{
var m = new ModMatrixOperator(mod);
var a = new long[2, 2];
a[0, 0] = a[0, 1] = a[1, 0] = 1;
a = m.Pow(a, n);
return(a[1, 0]);
}
// O(log n)
public static long GetValueWithMod(long p, long q, long a0, long a1, long n, long mod)
{
var m = new ModMatrixOperator(mod);
var a = new long[2, 2];
a[0, 0] = p;
a[0, 1] = -q;
a[1, 0] = 1;
a = m.Pow(a, n);
var v = m.Mul(a, new[] { a1, a0 });
return(v[1]);
}