#include <iostream>

using namespace std;


int getvalue(void);
double average(int,int,int);

int getvalue(void){
    int i;
    cerr << "Please enter a number: ";
    cin >> i;

    return i;
}

/*
 * average: Compute the average of 3 numbers.
 *
 * Input: 3 integers
 * Output: average
 */
double average(int x, int y, int z) {
    double avg;
    int total=x+y+z;

    avg=(double)total/3;

    return avg;
}

int main()
{
    double x=1;
    int i,j,k;

    i=getvalue();
    j=getvalue();
    k=getvalue();

    x=average(i,j,k);
    cout << x << endl;

    return 0;
}