#include <iostream>
#include <iomanip>

int main() {
    int first_day;
    std::cin >> first_day;
    int second_day = first_day / 100;
    int third_day = first_day % 100;
    double average = static_cast<double>(first_day + second_day + third_day) / 3;
    std::cout << std::fixed << std::setprecision(2) << average << std::endl;
    return 0;
}    
/**************************************************************
	Problem: 1618
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/