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import java.util.Scanner;

public class Main {
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        System.out.print("Введите N: ");
        int n = scanner.nextInt();

        if (n <= 0) {
            System.out.println("Ошибка");
        } else {

            int sum = 0;

            for (int i = 1; i <= n; i++) {
                sum = sum + i;
            }

            System.out.println("Сумма = " + sum);
        }
    }
}