// General imports

import java.util.Scanner;

public class DealEmOut {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    // Write code here

    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();

    int cards = 0;
    int value = a + b + c;

    if (a == 0)
      cards++;
    if (b == 0)
      cards++;
    if (c == 0)
      cards++;

    int known = 3 - cards;

    double adder = (416.0 - value) / (52.0 - known);

    double returner = value + adder * cards;

    System.out.printf("%.2f", returner);

    sc.close();
  }
}