/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
 
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
 
        int sum = A+B+C;
        double avg = sum/3.0;
        System.out.println(avg);
    }
 
}

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OQo2CjQ=

9
6
4