#include <bits/stdc++.h>

int main() {
  std::string str;
  for(int i = 0; i <= 100; ++i) {
    str += std::to_string(i);
  }
  int xs[300] = {};
  for(int i = 0; i < (int)str.size(); ++i) {
    xs[i] = str[i] - '0';
  }
  int n;
  scanf("%d", &n);
  for(int i = 0; i < 300; ++i) xs[i] *= n;
  for(int i = 300-1; i > 0; --i) {
    xs[i-1] += xs[i] / 10;
    xs[i]   %= 10;
  }
  printf("%d.", xs[0]);
  for(int i = 1; i < 300; ++i) {
    printf("%d", xs[i]);
  }
  printf("\n");
 
  return 0;
}