function Main(input) {
 var possibility;
 if(input % 2 == 0) {
   possibility = (input / 2) / input;
 } else {
   possibility = (Math.floor(input / 2) + 1 ) / input;
 }
 console.log(possibility);


}
Main(require('fs').readFileSync('/dev/stdin', 'utf-8'));
