#include <iostream>
struct stud{
    int id_student;
    double ball;
};

double sum(int* marks, int size){
    double sum;
    for(int i=0 ; i < size; i++){
        sum = sum + marks[i];
    }
    double rez = sum/size;
    return rez;
}

int main() {
    const int MARK_SIZE = 5;
    int marks[MARK_SIZE];
    for(int i=0; i < MARK_SIZE; i++){
        std::cout << "vvedit ocenku " << i+1 <<": ";
        std::cin >> marks[i];
    }
    struct stud stud1;
    stud1.id_student = 1;
    stud1.ball = sum(marks, MARK_SIZE);
    std::cout.precision(2);
    std::cout << "avareage ball of student with id#" << stud1.id_student << " is " << stud1.ball << std::endl;
    return 0;
}