python 等差数列末项计算方式

a1 = int(input())
a2 = int(input())
m = a2 - a1
n = int(input())
N = a1 + m*(n-1)
print(N)

a1 = int(input())
a2 = int(input())
n = int(input())
m = a2 - a1
for i in range(n-1):
 a1 += m
print(a1)

import sys
n = int(sys.stdin.readline().strip())
s = sys.stdin.readline()
s = list(map(int, s.split(' ')))
print(n)
print(s)
for i in range(len(s)-1):
    for j in range(i+1, len(s)):
      if s[i] >= s[j]:
        s[i], s[j] = s[j], s[i]
for j in range(1, len(s)-1):
  if s[j] - s[j-1] == s[j+1] - s[j]:
    flag = 1
  else:
    flag = 0
if flag == 1:
  print('Possible')
else:
  print('Impossible')