// Arup Guha
// 5/11/2016
// Solution to USACO 2016 Silver February Problem: Circular Barn

import java.util.*;
import java.io.*;

public class cbarn {

	public static void main(String[] args) throws Exception {

		// Read in data.
		BufferedReader stdin = new BufferedReader(new FileReader("cbarn.in"));
		int n = Integer.parseInt(stdin.readLine().trim());
		int[] cows = new int[n];
		for (int i=0; i<n; i++)
			cows[i] = Integer.parseInt(stdin.readLine().trim());

		int res = Integer.MAX_VALUE;

		// Try each rotation.
		for (int i=0; i<n; i++) {

			// Copy in this rotation to make life easy.
			int[] rot = new int[n];
			for (int j=0; j<n; j++)
				rot[j] = cows[(i+j)%n];

			// See if this rotation is possible.
			int total = 0;
			boolean flag = true;
			for (int j=n-1; j>=0; j--) {
				total += rot[j];
				if (total > n-j) {
					flag = false;
					break;
				}
			}

			// Can't do this.
			if (!flag) continue;

			// Find last 0 slot, initially.
			int cost = 0;
			int last = n-1;
			while (last >= 0 && rot[last] != 0) last--;

			// Now go backwards.
			for (int j=last-1; j>=0; j--) {

				// As long as this room has cows to donate.
				while (rot[j] > 0) {

					if (last == -1 || last < j) break;

					// Move a cow from j to last.
					rot[j]--;
					rot[last]++;
					cost = cost + (last-j)*(last-j);

					// Update last.
					while (last >= 0 && rot[last] != 0) last--;
				}
			}

			// See if this is better or not.
			res = Math.min(res, cost);
		}

		// Write result.
		PrintWriter out = new PrintWriter(new FileWriter("cbarn.out"));
		out.println(res);
		out.close();
		stdin.close();
	}
}