import java.util.Scanner;
class Demo03
{
public static void main(String[] args)
{
//juxing();
//shuzi();
/*Scanner sc = new Scanner(System.in);
System.out.println("输入行");
int m = sc.nextInt();
System.out.println("输入列");
int n = sc.nextInt();
juxing1(m,n);*/
Scanner sc = new Scanner(System.in);
System.out.println("输入");
double a = sc.nextDouble();
System.out.println("输入");
double b = sc.nextDouble();
System.out.println("输入");
double c = sc.nextDouble();
double avg = avg(a,b,c);
System.out.print(avg);
}
public static void juxing(){
for(int i = 0;i<3;i++){
for(int j = 0;j<3;j++){
System.out.print("*");
}
System.out.println();
}
}
public static int shuzi(){
Scanner sc = new Scanner(System.in);
System.out.println("输入");
int sz = sc.nextInt();
return sz;
}
public static void juxing1(int m,int n){
for(int i = 0;i<m;i++){
for(int j = 0;j<n;j++){
System.out.print("*");
}
System.out.println();
}
}
public static double avg(double a,double b,double c){
double avg = (a + b + c)/3;
return avg;
}
}