#include <bits/stdc++.h>
using namespace std;
int main() {
int N;
cin>>N;
int A[500];
for(int i=1;i<=N;i++)cin>>A[i];
int answer=0;
for(int i=1;i<=N;i++){
  answer=answer+abs(A[i]-i);
}
cout<<answer;
}