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

int main()
{
	ios::sync_with_stdio(false), cin.tie(0);
	int N;
	cin >> N;
	vector<int> B(N);
	for (int i = 0; i < N; i++) {
		cin >> B[i];
	}
	ll res = 0, pre = 0;
	for (int i = 0; i < N; i++) {
		res += abs(pre);
		pre += B[i] - 1;
	}
	cout << res << endl;
	return 0;
}