#include<stdio.h>
struct student{
    float marks[5];
};
int main(){
    struct student s;
    struct student *ptr = &s;
    float sum =0,avg;
    int i;
    for(i=0;i=5;i++){
        scanf("%f",&(ptr->marks[i]));
        sum+=ptr->marks[i];
    }
    avg=sum/5;
    printf("%.2f",avg);
    return 0;
}