import std.stdio, std.conv, std.array, std.string;
import std.algorithm;
import std.container;
import std.range;
import core.stdc.stdlib;
import std.math;

void main() {
  auto N = readln.chomp.to!int;
  int count = 0;
  foreach(i; 1..N+1) {
    if (i%2 == 1) count++; 
  }
  writeln(1.0f * count / N);
}
