#include <algorithm>
#include <functional>
#include <iostream>
#include <limits>
#include <vector>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int m, n;
    if (!(cin >> m >> n)) return 0;
    vector<long long> x(m + 1), prefix(m + 1);
    for (int i = 2; i <= m; ++i) {
        long long d;
        cin >> d;
        x[i] = x[i - 1] + d;
    }
    for (int i = 1; i <= m; ++i) prefix[i] = prefix[i - 1] + x[i];

    auto cost = [&](int l, int r) {
        int mid = (l + r) / 2;
        return x[mid] * (mid - l + 1LL) - (prefix[mid] - prefix[l - 1])
             + (prefix[r] - prefix[mid]) - x[mid] * (r - mid);
    };

    const long long inf = numeric_limits<long long>::max() / 4;
    vector<long long> previous(m + 1, inf), current(m + 1, inf);
    previous[0] = 0;
    for (int schools = 1; schools <= n; ++schools) {
        fill(current.begin(), current.end(), inf);
        function<void(int, int, int, int)> solve = [&](int left, int right, int opt_left, int opt_right) {
            if (left > right) return;
            int mid = (left + right) / 2;
            long long best = inf;
            int best_split = opt_left;
            int last = min(mid - 1, opt_right);
            for (int split = opt_left; split <= last; ++split) {
                long long candidate = previous[split] + cost(split + 1, mid);
                if (candidate < best) {
                    best = candidate;
                    best_split = split;
                }
            }
            current[mid] = best;
            solve(left, mid - 1, opt_left, best_split);
            solve(mid + 1, right, best_split, opt_right);
        };
        solve(schools, m, schools - 1, m - 1);
        previous.swap(current);
    }

    cout << previous[m] << '\n';
    return 0;
}