public static long Solve()
{
//long answer = 2L * 5L * 3L * 7L * 11L * 13L * 17L * 19L * 23L * 2L * 2L;
double ratio = 15499.0 / 94744.0; //0.1635881955585578
var primes = new PrimeNumbers();
long denominator = 1L;
double r = 1;
foreach (var prime in primes)
{
// 2L * 5L * 3L * 7L * 11L * 13L * 17L * 19L * 23L
r = (denominator * prime).phi() / ((denominator * prime) - 1.0);
if (r > ratio)
denominator *= prime;
else
{
r = denominator.phi() / (denominator - 1.0);
break;
}
}
while (r > ratio)
{
denominator *= primes.First();
r = denominator.phi() / (denominator - 1.0);
if (r < ratio)
break;
}
return denominator;
}