#include <iostream> using namespace std; int main() { int n; cin >> n; int sum = 0; for(int i=1;i<=n;++i){ if(i%2==0) sum+=i; } cout << sum << endl; return 0; }
#include <iostream> using namespace std; int main() { int n; cin >> n; int sum = 0; for(int i=1;i<=n;++i){ if(i%2==0) sum+=i; } cout << sum << endl; return 0; }