2024 2 17

# sum = 0
# b = 1
# while sum < a:
#     sum = sum +  b
#     b = b + 1
#
# print(b-1)

# a = int(input())
# n = 0
# while a!= 0:
#     print(' ' * n, '*' * a,sep='')
#     a = a-1
#     n = n + 1

# a, b, c, d = map(int,input().split())
# for i in range(d-1):
#     a = a * b + c
#
# print(a)