process.stdin.resume();

var lines = [];
var reader = require("readline").createInterface({
  input: process.stdin,
  output: process.stdout
});

reader.on("line", line => {
  var num = parseInt(line);
  var odd = 0;
  for (var i = 1; i <= num; i++) {
    if (i % 2 == 0) {
      odd++;
    }
  }
  p = odd / num;
  console.log(p);
});
