# i =3
# username = '大天天'
# password = 123
# while i > 0:
# name = input('请输入你的名字：')
# i -= 1
# if name==username:
# pwd = int(input('请输入你的密码：'))
# if pwd == password:
# print('登录成功，请稍后:')
# print('''恭喜你登陆成功！
# 欢迎用户进入
# username:%s
# password:%d
# ''' %(name,pwd))
# break
# else:
# print('你的密码错误:')
# print('你还有%d次机会'%(i))
# #continue#与下面if的用法 tab的变化
# if i == 0:#按向左一个tab后变化
# print('你的机会已经用完，结束本次操作')
# # break#不要也是一样的作用
# else:
# print('你的用户名错误！请重新输入')
# print('你还有%d次机会' %(i))
# i = 3
# username ='天'
# password =123
# while i > 0:
# name = input('请输入你的用户名')
# i -=1
# if name == username:
# pwd =int(input('请输入你密码'))
# # print('请输入密码')
# if pwd ==password :
# print('登录成功')
# print('''
# name:%s
# pwd:%d
# ''' %(name,password))
# break
# else:
# print('密码错误，请重新输入')
# print('你还有%d次机会' %(i))
# if i ==0:
# print('你的机会已经用完')
# else:
# print('用户名错误，请重新输入用户')
# print('你还有%d次机会' %(i))
# i = 3
# username = '大天天'
# password = 123
# while i > 0:
# name = input('请输入你名字:')
# i -=1
# if name == username:
# pwd = int(input('请输入你的密码:'))
# if pwd == 123:
# print('登陆成功')
# print('''
# 欢迎你登陆成功
# name:%s
# pwd:%d
# ''' %(name,pwd))
# break
# else:
# print('请重新输入密码')
# print('你还有%d次机会' %(i))
# # continue
# if i == 0:
# print('您的机会已经用完，请结束本次操作')
# else:
# print('你的用户名错误，请重新输入')
# print('你还有%d次机会' %(i))
# 输入一百以内的数
# i = 1
# while i <=100:
# print(i)
# i +=1
# i = 1
# sum =0
# while i <99:
# if i % 2 != 0:
# sum = sum + i
# else:
# sum = sum - i
# i += 1
# print(sum)
i = 0
j = -1
sum = 0
while i < 100:
i +=1
j = -j
if i == 88:
continue
else:
sum = sum + i*j
print(sum)
