#include <bits/stdc++.h>

//mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
//uniform_int_distribution<int>(1, 2000000)(rng);

using namespace std;
using ll = long long;

template <class T>
bool smax(T & x, T y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}

template <class T>
bool smin(T & x, T y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}


const int MOD = 998244353;

int sum(int x, int y) {
    if (x + y >= MOD) {
        return x + y - MOD;
    }
    return x + y;
}

int diff(int x, int y) {
//    cout << "DIFF " << x << " " << y << endl;
    if (x >= y) {
        return x - y;
    }
    return x + MOD - y;
}

int mult(int x, int y) {
//    cout << "MULT " << x << " " << y << endl;
    return (int) ((x * 1ll * y) % MOD);
}

int mypow(int x, ll p) {
    int ans = 1;
    while (p > 0) {
        if ((p & 1ll) == 1ll) {
            ans = mult(ans, x);
        }
        x = mult(x, x);
        p /= 2;
    }
//    cout << "POW " << ans << endl;
    return ans;
}

int inv(int x) {
    return mypow(x, MOD - 2);
}

int MAX = 5010;
vector<vector<double>> p(MAX, vector<double>(MAX));

void precalc() {
    p[1][0] = 1;
    p[2][0] = 0.5;
    for (int n = 3; n < MAX; ++n) {
        p[n][0] = 1. / n;
        for (int i = 1; i < n; ++i) {
            p[n][i] = (n - 1. - i) / n * p[n - 2][i - 1];
            if (i > 1) {
                p[n][i] += (i - 1.) / n * p[n - 2][i - 2];
            }
        }
    }
}

double PI = atan2l(0, -1);

void solve() {
    int n, p;
    cin >> n >> p;
    vector<double> a(2 * n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    for (int i = 0; i < n; ++i) {
        a[i + n] = a[i] + 360;
    }
    for (int i = 0; i < 2 * n; ++i) {
        a[i] *= PI / 180;
    }
    double ans = 0;
    for (int start = 0; start < n; ++start) {
        vector<vector<double>> dp(2 * n, vector<double>(p + 1, -2e5));
        dp[start][0] = 0;
        for (int i = start; i < start + n; ++i) {
            for (int k = 0; k < p; ++k) {
                for (int next = i + 1; next <= start + n; ++next) {
                    smax(dp[next][k + 1], dp[i][k] + sin(a[next] - a[i]) / 2);
                }
            }
        }
        for (int k = 0; k <= p; ++k) {
            smax(ans, dp[start + n][k]);
        }
    }
    cout << ans * 1e6 << "\n";
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    precalc();
    int t = 1;
//    for (int n = 1; n < 10; ++n) {
//        for (int i = 0; i < n; ++i) {
//            cout << p[n][i] << " " << "\n";
//        }
//        cout << "\n";
//    }
//    cin >> t;
    cout << fixed << setprecision(12);
    while (t--) {
        solve();
    }
    return 0;
}