#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
    int N;
    cin >> N;
    int B[N];
    for (int i = 0; i < N; i++) {
        cin >> B[i];
    }
    ll ans = 0;
    ll t = 0;
    for (int i = 0; i < N; i++) {
        t += B[i] - 1;
        ans += abs(t);
    }
    cout << ans << "\n";
    return 0;
}