Untitled

Bai 1:

#include <bits/stdc++.h>
using namespace std;
int main() {
	int n,tong;
	cin >> n;
	for (int i = 1; i <= n ; i ++) {
		tong += i;
	}
	cout << tong;
}

Bai 2:

#include <bits/stdc++.h>
using namespace std;
int main() {
	int n;
	cin >> n;
	int sophirain;
	sophirain += 2022;
	for (int i = 1; i <= n; i++) {
		sophirain += (i*2);
	}
        cout << sophirain;
}

Bai 3 :

#include <bits/stdc++.h>
using namespace std;
int main() {
	int n,k;
	cin >> n;
	while (n != 0) {
		n /= 10;
		k++;
	}
	cout << k;
}

Bai 4: