import java.util.*;
public class Main {
public static void main(String [] args) {
System.out.println("Hello");
System.out.println("World");
}
}*/
/*
import java.util.*;
public class Main {
public static void main(String [] args) {
System.out.println("Hello,");
System.out.println("World!");
}
}*/
/*1004
import java.util.*;
public class Main {
public static void main(String [] args) {
System.out.println("'Hello'");
}
}
입력문 - 자료형 (변수 선언)
//java의 자료형
정수 int long
실수 float double
문자 char 'k'
문자열 String "Hello"
불린 boolean true or false 의 값을 가지는 자료형
boolean a = true;
boolean b = false;
import java.util.*;
public class Main{
public static void main(String[] args) {
//1.스캐너 선언 (스캐너의 이름은 sc)
Scanner sc = new Scanner(System.in);
// 변수 선언 및 입력
//int a = sc.nextInt();
//int b = sc.nextInt();
//System.out.println(a+b);
//System.out.println("입력하신 a값은 "+a+"입니다. 그리고 b값은 "+b+"입니다.");
//long a = sc.nextLong();
//float a = sc.nextFloat();
//double b = sc.nextDouble();
// 문자열 선언 및 입력받기
// String a = sc.next(); //scanf("%s",str);
// String b = sc.next();
// //String a = sc.nextLine(); //gets(str);
// System.out.println(a);
// System.out.println(b);
//boolean a = sc.nextBoolean();
//System.out.println(a);
}
}
*/
/*
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner (System.in);
int a = sc.nextInt();
System.out.println(a);
}
}*/
/*
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner (System.in);
int a = sc.nextInt();
int b = sc.nextInt();
System.out.println(a+" "+b);
}
}*/
/*
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner (System.in);
int a = sc.nextInt();
System.out.println(a+" "+a+" "+a);
}
}*/
/*
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner (System.in);
float a = sc.nextFloat();
System.out.printf("%.6f",a);
//System.out.println(a);
}
}
+ - * / %
정수/정수 -> 정수몫
실수/정수
정수/실수
실수/실수 -> 실수
> < >= <= == !=
&& ||
1 or 0 (x) -> true or false
*/
/*
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner (System.in);
int a = sc.nextInt();
int b = a/60;
int c = a%60;
System.out.println(b+" "+c);
}
}*/
/*
import java.util.*;
public class Main{
public static void main(String[] args ) {
Scanner sc = new Scanner (System.in);
int a = sc.nextInt();
int b = sc.nextInt();
int c = a+b;
int d = a-b;
int e = a*b;
int f = a/b;
int g = a%b;
float h = (float)a/b;
System.out.println(c);
System.out.println(d);
System.out.println(e);
System.out.println(f);
System.out.println(g);
System.out.printf("%.2f",h);
}
}*/
import java.util.*;
public class main{
public static void main(String[] args) {
Scanner sc = new Scanner (System.in);
int a = sc.nextInt();
int b = sc.nextInt();
int c = sc.nextInt();
float d = (a+b+c)/3
System.out.printf("%.2f",d);
}
}