Problem:
Score : 300 points

Problem Statement

Snuke has an integer sequence A of length N.

He will freely choose an integer b.
Here, he will get sad if A_i and b+i are far from each other.
More specifically, the sadness of Snuke is calculated as follows:

abs(A_1 - (b+1)) + abs(A_2 - (b+2)) + ... + abs(A_N - (b+N))

Here, abs(x) is a function that returns the absolute value of x.

Find the minimum possible sadness of Snuke.

Constraints

1 \leq N \leq 2 \times 10^5

1 \leq A_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Print the minimum possible sadness of Snuke.

Sample Input 1

5
2 2 3 5 5

Sample Output 1

2

If we choose b=0, the sadness of Snuke would be abs(2-(0+1))+abs(2-(0+2))+abs(3-(0+3))+abs(5-(0+4))+abs(5-(0+5))=2.
Any choice of b does not make the sadness of Snuke less than 2, so the answer is 2.

Sample Input 2

9
1 2 3 4 5 6 7 8 9

Sample Output 2

0

Sample Input 3

6
6 5 4 3 2 1

Sample Output 3

18

Sample Input 4

7
1 1 1 1 2 3 4

Sample Output 4

6

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

 #include <stdio.h>
#include <stdlib.h>
             
int main(void){
int N;
int i;
scanf("%d",&N);
int A[N];
scanf("%d",&A[0]);
int min = A[0];
int max = A[0];
int summin = A[0] - 1;
for(i = 1;i<N;i++){
scanf("%d",&A[i]);
if(min > A[i]){
min = A[i];
}
if(max < A[i]){
max = A[i];
}
summin = summin + abs(A[i] - i - 1);
}

int sum;
for(int j = min;j<=max;j++){
sum = 0;
for(i = 0;i<N;i++){
sum = sum + abs(A[i] - j - i - 1);
}
if(summin > sum){
summin = sum;
}
}
printf("%d",summin);
return 0;
}