import std.algorithm, std.array, std.container, std.range;
import std.numeric, std.math, std.bigint, std.bitmanip, std.random;
import std.string, std.conv, std.stdio, std.typecons;

void main()
{
  auto s = readln.chomp.map!(to!int).array;
  s.sort();
  auto gi = s.group;

  auto r = fact(s.length.to!int) / gi.map!("a[1]").map!(a => fact(a)).reduce!("a * b");
  writeln(r - 1);
}

int fact(int n)
{
  return iota(n).map!("a + 1").reduce!("a * b");
}