sum-of-all-even-till-n-numbers.cpp

#include <iostream>
using namespace std;

int main()
{
    int n;
    cin >> n;

    int i = 1;
    int sum = 0;

    while (i <= n)
    {
        if (i % 2 == 0)
        {
            sum = sum + i;
        }
        i++;
    }

    cout << sum << endl;
}