[백준] 1021

# 1 2 3 4 5 6 7 8 9 10 # 0번
# 2 3 4 5 6 7 8 9 10 1 # 1번
# 9 10 1 3 4 5 6 7 8   # 3번
# 5 6 7 8 9 10 1 3 4   # 4번

from collections import deque

n, m = map(int, input().split())
queue = deque([i for i in range(1, n+1)])
# print(queue)
answer = list(map(int, input().split()))

cnt = 0
for i in range(m):
  if queue.index(answer[i]) >= len(queue)/2:
    while queue[0] != answer[i]:
      queue.rotate(1)
      cnt += 1
    queue.popleft()
  else:
    while queue[0] != answer[i]:
      queue.rotate(-1)
      cnt += 1
    queue.popleft()

print(cnt)