// Lecture : Introduction to C++ - Constant Expression
// OCSALY                 IDE : CLion

#include <cmath>
#include <iostream>

constexpr int traing(int i){
    return (i == 0) ? 0 : traing(i - 1) + i;
}

int main() {

    constexpr double pi =31.1415;
    constexpr double twopi = 2 * pi;

    return 0;
}