Buggy python submission (verdict: Time Limit Exceeded):
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Buggy python submission (verdict: Time Limit Exceeded):
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b = map(int, input().split())
qs = list(map(int, input().split()))
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Buggy python submission (verdict: Time Limit Exceeded):
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b = map(int, input().split())
qs = list(map(int, input().split()))
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min(dp_l.node[i+N-1] + i for i in range(1, n+1)))

Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Buggy python submission (verdict: Time Limit Exceeded):
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b = map(int, input().split())
qs = [a] + list(map(int, input().split()))
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
for i in range(q):
	x, y = qs[i], qs[i+1]
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	#print(res)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff

N = dp_l.n
print(total_diff + min(dp_l.node[i+N-1] + i for i in range(1, n+1)))

Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Buggy python submission (verdict: Time Limit Exceeded):
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1
		while self.n < size:
			self.n *= 2
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)//2
			self.node[x] = min(self.node[2*x+1], self.node[2*x+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b = map(int, input().split())
qs = [a] + list(map(int, input().split()))
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
for i in range(q):
	x, y = qs[i], qs[i+1]
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff

N = dp_l.n
print(total_diff + min(dp_l.node[i+N-1] + i for i in range(1, n+1)))


Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Buggy python submission (verdict: Time Limit Exceeded):
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1
		while self.n < size:
			self.n *= 2
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)//2
			self.node[x] = min(self.node[2*x+1], self.node[2*x+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b = map(int, input().split())
qs = [a] + list(map(int, input().split()))
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
for i in range(q):
	x, y = qs[i], qs[i+1]
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff

N = dp_l.n
print(total_diff + min(dp_l.node[i+N-1] + i for i in range(1, n+1)))

Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Buggy python submission (verdict: Time Limit Exceeded):
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1
		while self.n < size:
			self.n *= 2
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)//2
			self.node[x] = min(self.node[2*x+1], self.node[2*x+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b = map(int, input().split())
qs = [a] + list(map(int, input().split()))
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
for i in range(q):
	x, y = qs[i], qs[i+1]
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff

ans_l, ans_r = INF, INF
for i in range(1, n+1):
	ans_l = min(ans_l, dp_l.Access(i) + i)
	ans_r = min(ans_r, dp_r.Access(i) - i)

print(ans_l + total_diff)

Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Buggy python submission (verdict: Time Limit Exceeded):
import sys
def input():
	return sys.stdin.buffer.readline()[:-1]

INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1
		while self.n < size:
			self.n *= 2
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)//2
			self.node[x] = min(self.node[2*x+1], self.node[2*x+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b = map(int, input().split())
qs = [a] + list(map(int, input().split()))
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
for i in range(q):
	x, y = qs[i], qs[i+1]
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff

ans_l, ans_r = INF, INF
for i in range(1, n+1):
	ans_l = min(ans_l, dp_l.Access(i) + i)
	ans_r = min(ans_r, dp_r.Access(i) - i)

print(ans_l + total_diff)

Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))

Buggy python submission (verdict: Time Limit Exceeded):
INF = 10**15

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1
		while self.n < size:
			self.n *= 2
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)//2
			self.node[x] = min(self.node[2*x+1], self.node[2*x+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b = map(int, input().split())
qs = [a] + list(map(int, input().split()))
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
for i in range(q):
	x, y = qs[i], qs[i+1]
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff

ans_l, ans_r = INF, INF
for i in range(1, n+1):
	ans_l = min(ans_l, dp_l.Access(i) + i)
	ans_r = min(ans_r, dp_r.Access(i) - i)

print(ans_l + total_diff)

Fixed submission:
import sys
read = sys.stdin.buffer.read
INF = 10**12

class Rmin():
	def __init__(self, size):
		#the number of nodes is 2n-1
		self.n = 1 << (size.bit_length())
		self.node = [INF] * (2*self.n-1)

	def Access(self, x):
		return self.node[x+self.n-1]

	def Update(self, x, val):
		x += self.n-1
		self.node[x] = val
		while x > 0:
			x = (x-1)>>1
			self.node[x] = min(self.node[(x<<1)+1], self.node[(x<<1)+2])
		return

	#[l, r)
	def Get(self, l, r):
		L, R = l+self.n, r+self.n
		s = INF
		while L<R:
			if R & 1:
				R -= 1
				s = min(s, self.node[R-1])
			if L & 1:
				s = min(s, self.node[L-1])
				L += 1
			L >>= 1
			R >>= 1
		return s

n, q, a, b, *qs = map(int, read().split())
dp_l, dp_r = Rmin(n+1), Rmin(n+1)
dp_l.Update(b, -b)
dp_r.Update(b, b)

total_diff = 0
x = a
for y in qs:
	diff = abs(y - x)
	l_min = dp_l.Get(1, y)
	r_min = dp_r.Get(y, n+1)
	res = min(l_min + y, r_min - y)
	dp_l.Update(x, res - diff - x)
	dp_r.Update(x, res - diff + x)
	total_diff += diff
	x = y

N = dp_l.n
print(total_diff + min((l+r)>>1 for l, r in zip(dp_l.node[N:], dp_r.node[N:])))