#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
#define all(a) (a).begin(), (a).end()
#define X first
#define Y second

const int MOD = 1e9 + 7, MAXN = 2e6 + 1337;
const ld EPS = 1e-6;

void solve();

int main() {
#ifdef LOCAL
    freopen("../main_cpp/input.txt", "r", stdin);
#else
    cin.tie(nullptr)->sync_with_stdio(false);
#endif
    int _ = 1;
//    cin >> _;
    while (_--) {
        solve();
    }
}

const int INF = INT_MAX / 4;

const int R = 1 << 21;

struct Tree {
    vector<int> t;

    Tree() {
        t.resize(R * 2, 1);
    }

    void relax(int i) {
        while (i) {
            t[i] = min(t[i * 2], t[i * 2 + 1]), i /= 2;
        }
    }

    void add(int i) {
        t[i += R] = 1, i /= 2, relax(i);
    }

    void del(int i) {
        t[i += R] = 0, i /= 2, relax(i);
    }
    
    int mn(int ql, int qr, int node = 1, int nl = 0, int nr = R - 1) {
        if (ql <= nl && nr <= qr) return t[node];
        if (qr < nl || nr < ql) return 2;
        int nm = (nr + nl) / 2;
        return min(mn(ql, qr, node * 2, nl, nm), mn(ql, qr, node * 2 + 1, nm + 1, nr));
    }

//    int mn(int ql, int qr) {
//        int mn = 1;
//        for (ql += R, qr += R; ql <= qr; ql >>= 1, qr >>= 1) {
//            if (ql & 1) mn = min(mn, t[ql++]);
//            if (~qr & 1) mn = min(mn, t[qr--]);
//        }
//        return mn;
//    }
};

int n, k, m, q;

struct Round {
    Tree tree;
    vector<int> indv, indedge_dick, indedge_round;
    vector<int> c_dick, c_round;
    vector<int> pref;

    int all_sm;

    void init(const vector<tuple<int, int, int, int>> t) {
        c_dick.resize(MAXN, 1), c_round.resize(MAXN, 1), indv.resize(MAXN, -1), indedge_dick.resize(MAXN,
                                                                                                      -1), indedge_round.resize(
                MAXN, -1);
        pref.resize(MAXN, 0);
        all_sm = 0;
        for (int i = 0; i < t.size(); ++i) {
            tree.add(i);
            auto [w, vertex, index_edge, f] = t[i];
            indv[vertex] = i;
            all_sm += w;
            if (f) {
                indedge_dick[index_edge] = i;
            } else {
                indedge_round[index_edge] = i;
            }
            pref[i] = w + (i > 0 ? pref[i - 1] : 0);
        }
    }

    void change_dick(int i) {
        c_dick[i] = -c_dick[i];
        if (indedge_dick[i] == -1) return;
        if (c_dick[i] == -1) {
            tree.del(indedge_dick[i]);
        } else {
            tree.add(indedge_dick[i]);
        }
    }

    void change_round(int i) {
        c_round[i] = -c_round[i];
        if (indedge_round[i] == -1) return;
        if (c_round[i] == -1) {
            tree.del(indedge_round[i]);
        } else {
            tree.add(indedge_round[i]);
        }
    }

    int gett(int l, int r) {
        return pref[r - 1] - (l == 0 ? 0 : pref[l - 1]);
    }

    int get(int l, int r) {
        if (tree.mn(l, r - 1) == 0) return INF;
        return gett(l, r);
    }

    int find(int u, int v) {
        if (u == v) return 0;
        int i1 = indv[u], i2 = indv[v];
        if (min(i1, i2) == -1) return INF;
        if (i1 > i2) swap(i1, i2);
        int ans = get(i1, i2);
        if (min(tree.mn(i2, R - 1), tree.mn(0, i1 - 1)) > 0) {
            ans = min(ans, all_sm - gett(i1, i2));
        }
        return ans;
    }
};

void solve() {
    cin >> n >> k >> m >> q;
    vector<int> a(n + 1);
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
    }
    ++m;
    vector<int> b(m);
    for (auto &i: b) {
        cin >> i;
    }
    Round roundleft, roundright;
    {
        vector<tuple<int, int, int, int>> t; // {w, vertex, index_edge}
        for (int i = 1; i < k; ++i) {
            t.emplace_back(a[i], i, i, 0);
        }
        for (int i = m - 1, v = n + m; i >= 0; --i, --v) {
            t.emplace_back(b[i], (v == n + m ? k : v), i, 1);
        }
        roundright.init(t);
    }
    {
        vector<tuple<int, int, int, int>> t; // {w, vertex, index_edge}
        for (int i = k; i <= n; ++i) {
            t.emplace_back(a[i], i, i, 0);
        }
        for (int i = 0, v = n; i < m; ++i, ++v) {
            t.emplace_back(b[i], (v == n ? 1 : v), i, 1);
        }
        roundleft.init(t);
    }
    auto get = [&](int u, int v) -> int {
        return min(roundleft.find(u, v), roundright.find(u, v));
    };
    while (q--) {
        char c;
        cin >> c;
        if (c == 'c') {
            int i;
            cin >> i;
            roundleft.change_round(i), roundright.change_round(i);
        } else if (c == 'x') {
            int i;
            cin >> i;
            roundleft.change_dick(i), roundright.change_dick(i);
        } else {
            int u, v;
            cin >> u >> v;
            int dst1k = get(1, k);
            int ans = get(u, v);
            ans = min({ans, min(get(u, 1) + get(k, v), get(u, k) + get(1, v)) + dst1k});
            ans = min({ans, get(u, 1) + get(1, v), get(u, k) + get(k, v)});
            cout << (ans >= INF ? "impossible" : to_string(ans)) << "\n";
        }
    }
}