#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int n;
  cin >> n;
  vector<int> x, y;
  REP (i, n) {
    int b;
    cin >> b;
    if (!b)
      x.push_back(i);
    else if (b > 1) {
      REP (j, b-1)
        y.push_back(i);
    }
  }

  int ret = 0;
  REP (i, x.size())
    ret += abs(x[i] - y[i]);
  cout << ret << endl;
  
  return 0;
}