#include <bits/stdc++.h>
using namespace std;

using ll = long long;

int main() {
    int n;
    cin >> n;
    vector<int> b(n);
    for (int i = 0; i < n; i++) {
        cin >> b.at(i);
    }

    ll ans = 0;
    int sum = 0;
    for (int i = 0; i < n; i++) {
        sum += b.at(i);
        ans += (ll)abs(i + 1 - sum);
    }
    cout << ans << endl;
}