"""练习 25 进阶版：用 sum 和 range 计算循环累加结果。"""
n = int(input())
if n < 0:
    raise ValueError("n 必须为非负整数")

loop_total = sum(range(1, n + 1))
formula_total = n * (n + 1) // 2
print("loop result and additions:", loop_total, n)
print("formula result:", formula_total)
print("results match:", loop_total == formula_total)