#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (auto i = a; i < (b); ++i)
#define repr(i, a, b) for (auto i = (a) - 1; i >= (b); --i)
#define pb push_back
#define eb emplace_back
#define all(x) begin(x), end(x)
#define sz(x) int((x).size())

using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;
using vii = vector<pii>;

template<class T>
inline bool cmax(T &a, const T& b) {
    return a < b ? a = b, 1 : 0;
}

template<class T>
inline bool cmin(T &a, const T &b) {
    return b < a ? a = b, 1 : 0;
}

const int inf = 0x3f3f3f3f;
const ll linf = 1e18;
const double dinf = numeric_limits<double>::infinity();

using ld = long double;

const double pi = acos(-1);

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    int n;
    cin >> n;
    vi t(n + 1);
    rep(i, 1, n + 1) {
        cin >> t[i];
    }
    int m;
    cin >> m;
    vi q(m);
    
    rep(i, 0, m) {
        cin >> q[i];
    }

    vector< vector<double> > dp(n + 1, vector<double>(m, dinf));
    rep(i, 0, m) {
        if (q[i] == t[1]) {
            dp[1][i] = 1;
        }
    }

    auto dist = [&](int i, int j) {
        return hypot(cos((2 * pi * i) / m) - cos((2 * pi * j) / m), sin((2 * pi * i) / m) - sin((2 * pi * j) / m));
    };

    // cerr << dist(0, 2) << endl;

    rep(i, 2, n + 1) {
        rep(j, 0, m) {
            if (q[j] != t[i]) {
                continue;
            }
            rep(k, 0, m) {
                if (q[k] != t[i - 1]) {
                    continue;
                }
                cmin(dp[i][j], dp[i - 1][k] + dist(j, k));
            }
        }
    }

    double ans = dinf;
    rep(j, 0, m) {
        cmin(ans, dp[n][j]);
    }
    cout << fixed << setprecision(15) << ans << '\n';

    // rep(i, 1, n + 1) {
    //     rep(j, 0, m) {
    //         cerr << dp[i][j] << ' ';
    //     }
    //     cerr << endl;
    // }

    return 0;
}