#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep3(i, l, n) for (int i = l; i < (n); ++i)
#define sz(v) (int)v.size()
#define inf (int)(1e9+7)
#define abs(x) (x >= 0 ? x : -(x))
#define ceil(a, b) a / b + !!(a % b)
template<typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { if (a > b) { a = b; return 1; } return 0; }
template<typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { if (a < b) { a = b; return 1; } return 0; }
template<typename T> T gcd(T a, T b) { if (b == 0) return a; return gcd(b, a % b); }






int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    
    ll ans = 0;
    queue<int> q;
    queue<int> q2;
    
    int n;
    cin >> n;
    rep(i, n) {
        int a;
        cin >> a;
        if (a == 0) q.push(i);
        else if (a > 1) {
            rep(j, a - 1) q2.push(i);
        }
    }
    
    while (sz(q)) {
        ans += abs(q.front() - q2.front());
        q.pop(); q2.pop();
    }
    cout << ans << endl;
}