#include <stdio.h>
#include <algorithm>
#define MaxN 100000
#define abs(a) ((a)>0?(a):-(a))
#define get_min(a, b) ((a)<(b)?(a):(b))
int N;
int X[MaxN];
long long D, Ans;
struct bot {
int x, index;
} Bot[MaxN];
bool compare(bot a, bot b){
return (long long)a.x * (long long)b.index < (long long)b.x * (long long)a.index;
}
long long get_cost(long long d){
int i;
long long sum = 0;
for (i=1; i<N; i++){
sum += abs(i*d - X[i]);
}
return sum;
}
int main(void){
int i;
long long sum, t;
scanf("%d", &N);
for (i=0; i<N; i++) scanf("%d", &X[i]);
for (i=1; i<N; i++) X[i] -= X[0];
for (i=1; i<N; i++){
Bot[i].x = X[i];
Bot[i].index = i;
}
std::sort(Bot+1, Bot+N, compare);
sum = N; sum = sum*(sum-1)/2;
t = 0;
for (i=1; i<N; i++){
if (t+1 <= (sum+1)/2 && (sum+1)/2 <= t+Bot[i].index){
break;
}
t += Bot[i].index;
}
D = Bot[i].x / Bot[i].index;
printf("%lld\n", get_min(get_cost(D), get_cost(D+1)));
// printf("%lld\n", get_min(get_cost(976), get_cost(977)));
return 0;
}
