process.stdin.setEncoding('utf-8');
process.stdin.on('data', (input) => {
  var arry = input.split(' ');
  var r = parseInt(arry[0]);
  var pi = Math.PI;
  var result = 2 * pi * r;

  var output = result.tofixed(5)

  console.log(output + ' ' + output);
})

