Buggy python submission (verdict: Runtime Error):
import fractions
import sys
from functools import reduce
import math

input = sys.stdin.readline

def main():
    n, m = input_list()
    x = list(sorted(input_list()))
    diffs = []
    for i in range(1, m):
        a = x[i] - x[i-1]
        diffs.append((i, a))
    dd = list(sorted(diffs, key=lambda v: v[1], reverse=True))
    args = [d[0] for d in dd[:n-1]]
    r = divide_list(x, args)
    ans = 0
    for xx in r:
        ans += max(xx) - min(xx)
    print(ans)


def divide_list(l, args):
    result = []
    pre = 0
    for i, a in enumerate(args):
        if i != 0:
            pre = args[i-1]
        result.append(l[pre:a])
        if i == len(args) - 1:
            result.append(l[a:])
    return result

def divide_two(n):
    c = 0
    while True:
        if c >= 2:
            break
        if n % 2 != 0:
            break
        n //= 2
        c += 1
    return c

def get_camulative(l):
    import itertools
    # 累積和
    return [0] + list(itertools.accumulate(l))

def combinations_count(n, r):
    return math.factorial(n) // (math.factorial(n - r) * math.factorial(r))


def input_list():
    return list(map(int, input().split()))


def input_list_str():
    return list(map(str, input().split()))


def lcm_base(x, y):
    return (x * y) // fractions.gcd(x, y)


def lcm_list(numbers):
    return reduce(lcm_base, numbers, 1)


def gcd(*numbers):
    return reduce(fractions.gcd, numbers)


def gcd_list(numbers):
    return reduce(fractions.gcd, numbers)


if __name__ == "__main__":
    main()


Fixed submission:
N, M = map(int, input().split())
X = list(map(int, input().split()))

if M <= N:
  print(0)
  exit(0)
  
X.sort()
intervals = []
for i in range(M-1):
  intervals.append(X[i+1] - X[i])
  
intervals.sort()
R = max(X) - min(X)
for _ in range(N-1):
  R -= intervals.pop()
  
print(R)

Buggy python submission (verdict: Runtime Error):
def main():
  n, m = input_list()
  if n >= m:
    print(0)
    exit(0)
  x = list(set(input_list()))
  sx = list(sorted(x))
  diffs = []
  for i, xv in enumerate(range(len(x)-1)):
    diff = abs(sx[i+1]-sx[i])
    diffs.append((i, diff))
  sd = list(sorted(diffs, key=lambda x: x[1], reverse=True))
  
  points = []
  for i in range(n-1):
    if i > len(sd)-1:
      break
    points.append(sd[i][0])
  r = chunk_list(points, sx)
  ans = 0
  for v in r:
    ans += max(v) - min(v)
  print(ans)
    

def chunk_list(index_list, data):
  result = []
  start = 0
  for i in index_list:
    result.append(data[start:i+1])
    start = i+1
  result.append(data[start:len(data)])
  return result
  
def count_section_by_zero(data):
  count = 0
  flg = False
  start = 0
  for i, d in enumerate(data):
    if flg is False and d != 0:
      count += 1
      flg = True
      
    if d == 0:
      flg = False
  return count
  
def input_list():
  return list(map(int, input().split()))

def input_list_str():
  return map(str, input().split())

def lcm_base(x, y):
    return (x * y) // fractions.gcd(x, y)

def lcm_list(numbers):
    return reduce(lcm_base, numbers, 1)

def gcd(*numbers):
    return reduce(fractions.gcd, numbers)

def gcd_list(numbers):
    return reduce(fractions.gcd, numbers)

# 2で割り切れる回数
def divide_two(arg):
  c = 0
  while True:
    if c >= 2:
      break
    if arg % 2 != 0:
      break
    arg //= 2
    c += 1
  return c

# 素因数分解
def prime_factorize(n):
    a = []
    while n % 2 == 0:
        a.append(2)
        n //= 2
    f = 3
    while f * f <= n:
        if n % f == 0:
            a.append(f)
            n //= f
        else:
            f += 2
    if n != 1:
        a.append(n)
    return a

import math
import fractions
import collections
from functools import reduce
main()

Fixed submission:
N, M = map(int, input().split())
X = list(map(int, input().split()))

if M <= N:
  print(0)
  exit(0)
  
X.sort()
intervals = []
for i in range(M-1):
  intervals.append(X[i+1] - X[i])
  
intervals.sort()
R = max(X) - min(X)
for _ in range(N-1):
  R -= intervals.pop()
  
print(R)

Buggy python submission (verdict: Runtime Error):
def main():
  n, m = input_list()
  if n >= m:
    print(0)
    exit(0)
  x = input_list()
  sx = list(sorted(x))
  diffs = []
  for i, xv in enumerate(range(m-1)):
    diff = abs(sx[i+1]-sx[i])
    diffs.append((i, diff))
  sd = list(sorted(diffs, key=lambda x: x[1], reverse=True))
  
  points = []
  for i in range(n-1):
    points.append(sd[i][0])
  
  r = chunk_list(points, sx)
  ans = 0
  for v in r:
    ans += max(v) - min(v)
  print(ans)
    

def chunk_list(index_list, data):
  result = []
  start = 0
  for i in index_list:
    result.append(data[start:i+1])
    start = i+1
  result.append(data[start:len(data)])
  return result
  
def count_section_by_zero(data):
  count = 0
  flg = False
  start = 0
  for i, d in enumerate(data):
    if flg is False and d != 0:
      count += 1
      flg = True
      
    if d == 0:
      flg = False
  return count
  
def input_list():
  return list(map(int, input().split()))

def input_list_str():
  return map(str, input().split())

def lcm_base(x, y):
    return (x * y) // fractions.gcd(x, y)

def lcm_list(numbers):
    return reduce(lcm_base, numbers, 1)

def gcd(*numbers):
    return reduce(fractions.gcd, numbers)

def gcd_list(numbers):
    return reduce(fractions.gcd, numbers)

# 2で割り切れる回数
def divide_two(arg):
  c = 0
  while True:
    if c >= 2:
      break
    if arg % 2 != 0:
      break
    arg //= 2
    c += 1
  return c

# 素因数分解
def prime_factorize(n):
    a = []
    while n % 2 == 0:
        a.append(2)
        n //= 2
    f = 3
    while f * f <= n:
        if n % f == 0:
            a.append(f)
            n //= f
        else:
            f += 2
    if n != 1:
        a.append(n)
    return a

import math
import fractions
import collections
from functools import reduce
main()

Fixed submission:
N, M = map(int, input().split())
X = list(map(int, input().split()))

if M <= N:
  print(0)
  exit(0)
  
X.sort()
intervals = []
for i in range(M-1):
  intervals.append(X[i+1] - X[i])
  
intervals.sort()
R = max(X) - min(X)
for _ in range(N-1):
  R -= intervals.pop()
  
print(R)