import sys
from collections import deque, Counter
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 63 - 1
mod = 998244353
import heapq
class MedianHeap():
    def __init__(self):
        self.top = []
        self.bottom = []
    def __len__(self):
        return len(self.top) + len(self.bottom)
    def add(self, x):
        heapq.heappush(self.top, x)
        while len(self.top) - 2 >= len(self.bottom):
            heapq.heappush(self.bottom, -heapq.heappop(self.top))
        while self.top and self.bottom and self.top[0] < -self.bottom[0]:
            x = heapq.heappop(self.top)
            y = heapq.heappop(self.bottom)
            heapq.heappush(self.top, -y)
            heapq.heappush(self.bottom, -x)
    def med(self):
        if len(self) % 2:
            return self.top[0], self.top[0]
        else:
            return -self.bottom[0], self.top[0]
n = ii()
a = li()
a.sort()
a = [a[i] - i for i in range(n)]

stack = []
for V in a:
    M = MedianHeap()
    M.add(V)
    stack.append(M)
    while len(stack) >= 2:
        X = stack.pop()
        Y = stack.pop()
        m2, M2 = X.med()
        m1, M1 = Y.med()
        if m1 < M2:
            stack.append(Y)
            stack.append(X)
            break
        else:
            if len(X) < len(Y):
                for v in X.top:
                    Y.add(v)
                for v in X.bottom:
                    Y.add(-v)
                stack.append(Y)
            else:
                for v in Y.top:
                    X.add(v)
                for v in Y.bottom:
                    X.add(-v)
                stack.append(X)

P = [len(stack[i]) for i in range(len(stack))]
cnt = 0
b = [0] * n
for i, v in enumerate(P):
    med = max(b[cnt - 1], stack[i].med()[0])
    for x in range(v):
        b[cnt] = med
        cnt += 1


ans = sum([abs(a[i] - b[i]) for i in range(n)])
print(ans)