#include<stdio.h>


int main()
{
    int    arr[5];
    int    i=0;
    int     sum=0;
    float    average;

    FILE    *fp;
    fp    =fopen("data.in","r");
    if(fp == NULL){
        fprintf(stderr,"can't open file!\n");
        fclose(fp);
        return 1;
    }
    while(fscanf(fp,"%d",&arr[i])==1);
    i++;
    sum=arr[0]+arr[1]+arr[2]+arr[3]+arr[4];
    average = sum/5;

    printf("%.2f\n",average);
   
    return 0;



}