floyd triangle

class Main {
    public static void main(String[] args) {
        int num = 1;
        int n = 5;
        for(int i = 1; i <= n; i++){
            for(int j = 1; j <= i; j++){
                System.out.print(num);
                num++;
            }
            System.out.println();
        }
    }
}