[B1059][좋은 구간][python]

https://www.acmicpc.net/problem/1059

---

L = int(input())
L_list = [0] + sorted(list(map(int,input().split())))
N = int(input())
start = 0

if N in L_list: 
    print(0)
    
else: 
    for i in L_list:
        if N > i:
            start = i + 1 
        else:
            end = i - 1 
            break
    print(end - start + (end - N) * (N - start))