#include <bits/stdc++.h>

using i64 = long long;

constexpr i64 inf = 1E18;

i64 square(i64 n) {
    return n * n;
}

void chmin(i64 &a, i64 b) {
    if (b < a) {
        a = b;
    }
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n;
    while (std::cin >> n) {
        std::vector<int> x(n);
        for (int i = 0; i < n; i++) {
            std::cin >> x[i];
        }
        
        if (n == 1) {
            std::cout << 0 << "\n";
            continue;
        }
        
        i64 ans = inf;
        std::vector dp(n, std::vector<i64>(n, inf)), f(n, std::vector<i64>(n));
        for (int i = 0; i < n; i++) {
            i64 sum = 0;
            for (int j = i + 1; j < n; j++) {
                sum += square(x[j] - x[j - 1]);
                f[i][j] = sum;
            }
        }
        for (int i = 0; i < n - 1; i++) {
            int k = i;
            i64 min = inf, min1 = inf, min2 = inf;
            std::vector<i64> pre(n, inf);
            for (int j = 0; j < i; j++) {
                pre[j + 1] = std::min(pre[j], dp[i][k]);
                chmin(min1, dp[j][i]);
                chmin(min2, dp[i][j] - square(std::min(x[i + 1] - x[i], x[i] - x[j])));
            }
            for (int j = i + 1; j < n; j++) {
                if (i == 0) {
                    dp[i][j] = dp[j][i] = f[i][j] + square(x[j] - x[i]);
                } else {
                    while (k > 0 && x[i] - x[k - 1] <= x[j] - x[i]) {
                        k--;
                        chmin(min, dp[i][k] - square(x[i] - x[k]));
                    }
                    chmin(dp[i][j], std::min(min + square(x[j] - x[i]), pre[k]) + f[i][j]);
                    chmin(dp[i][j], pre[i] + std::max(0LL, square(x[j] - x[i]) - square(x[i] - x[i - 1])) + f[i][j]);
                    chmin(dp[j][i], min1 + f[i][j] + square(x[j] - x[i]) - square(std::min(x[i] - x[i - 1], x[i + 1] - x[i])));
                    chmin(dp[j][i], min2 + f[i][j] + square(x[j] - x[i]));
                }
            }
        }
        for (int i = 0; i < n - 1; i++) {
            chmin(ans, dp[i][n - 1]);
            chmin(ans, dp[n - 1][i]);
        }
        std::cout << ans << "\n";
    }
    
    return 0;
}