Buggy python submission (verdict: Runtime Error):
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

aa=sorted(a)
if n%2==0:
  b=(aa[n/2-1]+aa[n/2])/2
else:
  b=aa[int((n-1)/2)]

s=0
for i in aa:
  s+=abs(i-b)
print(s)



Fixed submission:
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

aa=sorted(a)
if n%2==0:
  b=(aa[int(n/2-1)]+aa[int(n/2)])/2
else:
  b=aa[int((n-1)/2)]

s=0
for i in aa:
  s+=abs(i-b)
print(int(s))

Buggy python submission (verdict: Runtime Error):
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

import math
import numpy as np

aa=np.asarray(a)
b=math.floor(np.sum(aa)/n)

def p(b,k):
  s=np.sum(np.abs(aa-b))
  t=np.sum(np.abs(aa-b-1))
  if s>t:
    if k==-1:
      print(t)
    else:
      return p(b+1,1)
  elif s==t:
    print(s)
  else:
    if k==1:
      print(s)
    else:
      return p(b-1,-1)
  
p(b,0)



Fixed submission:
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

aa=sorted(a)
if n%2==0:
  b=(aa[int(n/2-1)]+aa[int(n/2)])/2
else:
  b=aa[int((n-1)/2)]

s=0
for i in aa:
  s+=abs(i-b)
print(int(s))

Buggy python submission (verdict: Runtime Error):
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

import math
#import statistics
#b=statistics.median(a)
b=math.floor(sum(a)/n)

import numpy as np

aa=np.asarray(a)
def p(b,k):
  s=np.sum(np.abs(aa-b))
  t=np.sum(np.abs(aa-b-1))
  if s>t:
    if k==-1:
      print(t)
    else:
      return p(b+1,1)
  elif s==t:
    print(s)
  else:
    if k==1:
      print(s)
    else:
      return p(b-1,-1)
  
p(b,0)



Fixed submission:
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

aa=sorted(a)
if n%2==0:
  b=(aa[int(n/2-1)]+aa[int(n/2)])/2
else:
  b=aa[int((n-1)/2)]

s=0
for i in aa:
  s+=abs(i-b)
print(int(s))

Buggy python submission (verdict: Time Limit Exceeded):
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

import math
#import statistics
#b=statistics.median(a)
b=math.floor(sum(a)/n)


def p(b,k):
  s=0
  t=0
  for i in a:
      s+=abs(i-b)
      t+=abs(i-b-1) 
  if s>t:
    if k==-1:
      print(t)
    else:
      return p(b+1,1)
  elif s==t:
    print(s)
  else:
    if k==1:
      print(s)
    else:
      return p(b-1,-1)
  
p(b,0)



Fixed submission:
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

aa=sorted(a)
if n%2==0:
  b=(aa[int(n/2-1)]+aa[int(n/2)])/2
else:
  b=aa[int((n-1)/2)]

s=0
for i in aa:
  s+=abs(i-b)
print(int(s))

Buggy python submission (verdict: Time Limit Exceeded):
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

import math
#import statistics
#b=statistics.median(a)
b=math.floor(sum(a)/n)


def p(b,k):
  s=0
  for i in a:
      s+=abs(i-b)
  t=0
  for i in a:
      t+=abs(i-b-1) 
  if s>t:
    if k==-1:
      print(t)
    else:
      return p(b+1,1)
  elif s==t:
    print(s)
  else:
    if k==1:
      print(s)
    else:
      return p(b-1,-1)
  
p(b,0)



Fixed submission:
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

aa=sorted(a)
if n%2==0:
  b=(aa[int(n/2-1)]+aa[int(n/2)])/2
else:
  b=aa[int((n-1)/2)]

s=0
for i in aa:
  s+=abs(i-b)
print(int(s))

Buggy python submission (verdict: Time Limit Exceeded):
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

import math
b=math.floor(sum(a)/n)


def p(b,k):
  s=0
  for i in a:
      s+=abs(i-b)
  t=0
  for i in a:
      t+=abs(i-b-1) 
  if s>t:
    if k==-1:
      print(t)
    else:
      return p(b+1,1)
  else:
    if k==1:
      print(s)
    else:
      return p(b-1,-1)
  
p(b,0)



Fixed submission:
n = int(input())
a= [int(i) for i in input().split()]

for i in range(len(a)):
    a[i]-=i+1

aa=sorted(a)
if n%2==0:
  b=(aa[int(n/2-1)]+aa[int(n/2)])/2
else:
  b=aa[int((n-1)/2)]

s=0
for i in aa:
  s+=abs(i-b)
print(int(s))