#include <bits/stdc++.h>

using i64 = long long;

constexpr i64 inf = 1E18;

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)), f(n, std::vector<i64>(n));
        for (int i = 0; i < n; i++) {
            i64 sum = 0;
            int max = 0;
            for (int j = i + 1; j < n; j++) {
                sum += 1LL * (x[j] - x[j - 1]) * (x[j] - x[j - 1]);
                max = std::max(max, x[j] - x[j - 1]);
                f[i][j] = sum - 1LL * max * max;
            }
        }
        for (int i = 0; i < n; i++) {
            int k = i;
            i64 min = inf;
            std::vector<i64> pre(n, inf);
            for (int j = 0; j < i; j++) {
                pre[j + 1] = std::min(pre[j], dp[j][i] + 1LL * (x[i] - x[j]) * (x[i] - x[j]));
            }
            for (int j = i + 1; j < n; j++) {
                if (i == 0) {
                    dp[i][j] = f[i][j] + 1LL * (x[j] - x[i]) * (x[j] - x[i]);
                } else {
                    while (k > 0 && x[i] - x[k - 1] <= x[j] - x[i]) {
                        k--;
                        min = std::min(min, dp[k][i]);
                    }
                    dp[i][j] = std::min(min + 1LL * (x[j] - x[i]) * (x[j] - x[i]), pre[k]) + f[i][j];
                }
            }
        }
        for (int i = 0; i < n - 1; i++) {
            ans = std::min(ans, dp[i][n - 1] + 1LL * (x[n - 1] - x[i]) * (x[n - 1] - x[i]));
        }
        std::cout << ans << "\n";
    }
    
    return 0;
}