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

int main() {
	int n, a, ossz = 0; cin >> n;
	vector<int> inp;
	for (int i = 1; i <= n; i++) {
		cin >> a;
		for (int j = 0; j < a; j++) {
			inp.push_back(i);
			ossz++;
		}
	}
	vector<vector<int>> dp(ossz+1, vector<int>(n+1, 1000000000));
	for (int i = 0; i <= n; i++) {
		dp[0][i] = 0;
	}

	for (int y = 1; y <= ossz; y++) {
		for (int x = 1; x <= n; x++) {
			if ((dp[y-1][x-1]+abs(inp[y-1]-x)) > dp[y][x-1]) {
				dp[y][x] = dp[y][x-1];
			} else {
				dp[y][x] = (dp[y-1][x-1]+abs(inp[y-1]-x));
			}
		}
	}

	//TÁBLA
	/*
	for (vector<int> v : dp) {
		for (int i : v) {
			cout << i << " ";
		}
		cout << "\n";
	}
	*/
	cout << dp[ossz][n];
}