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

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int, int> pii;
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)x.size();
#define rep(i,j,k) for (int i = j; i < (k); i++)
#define in(mp, v) (mp.find(v) != mp.end())
#define smx(a, b) a = max(a, b)
#define smn(a, b) a = min(a, b)
#define pb push_back
#define endl '\n'

const ll MOD = 1e9 + 7;
const ld EPS = 1e-9;

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

    int n, k, m, q; cin >> n >> k >> m >> q;
    vector<ll> cpf(n+1), xpf(m+1);
    for (int i = 1; i <= n; i++) {
        cin >> cpf[i];
        cpf[i] += cpf[i-1];
    }

    for (int i = 0; i <= m; i++) {
        cin >> xpf[i];
        if (i > 0) xpf[i] += xpf[i-1];
    }

    set<int> bkc, bkx;
    auto qrc = [&](int a, int b) {
        if (a > b) return 0ll;
        auto lb = bkc.lower_bound(a);
        if (lb != bkc.end() && *lb <= b) return MOD;
        return cpf[b] - cpf[a-1];
    };
    auto qrx = [&](int a, int b) {
        if (a > b) return 0ll;
        auto lb = bkx.lower_bound(a);
        if (lb != bkx.end() && *lb <= b) return MOD;
        if (a <= 0) return xpf[b];
        return xpf[b] - xpf[a-1];
    };

    for (int qi = 0; qi < q; qi++) {
        string qt; cin >> qt;
        if (qt[0] == 'c') {
            int x; cin >> x;
            if (in(bkc, x)) {
                bkc.erase(x);
            } else {
                bkc.insert(x);
            }
        } else if (qt[0] == 'x') {
            int x; cin >> x;
            if (in(bkx, x)) {
                bkx.erase(x);
            } else {
                bkx.insert(x);
            }
        } else {
            int i, j; cin >> i >> j;
            if (i > j) swap(i, j);
            if (i > n && j > n) {
                // case 1: both on line
                i -= n; j -= n;
                ll a1 = qrx(i, j-1);
                ll xout = qrx(0, i-1) + qrx(j, m);
                ll a2 = qrc(1, k-1) + xout;
                ll a3 = qrc(k, n) + xout;
                ll ans = min({a1, a2, a3});
                if (ans >= MOD) cout << "impossible\n";
                else cout << ans << '\n';
            } else if (i <= n && j > n) {
                // case 2: one on line, one off
                ll xt = qrx(0, j-1), xb = qrx(j, m);
                j -= n;
                if (i < k) {
                    // case 2.1: off line is less than k
                    ll ct = qrc(1, i-1);
                    ll a1 = xt + ct;
                    ll a2 = xb + qrc(i, k-1);
                    ll a3 = xt + qrc(i, n);
                    ll a4 = xb + qrc(k, n) + ct;
                    ll ans = min({a1, a2, a3, a4});
                    if (ans >= MOD) cout << "impossible\n";
                    else cout << ans << '\n';
                } else {
                    // case 2.2: off line is greater than k
                    ll ct = qrc(i, n);
                    ll a1 = xt + ct;
                    ll a2 = xb + qrc(k, i-1);
                    ll a3 = xt + qrc(1, i-1);
                    ll a4 = xb + qrc(1, k-1) + ct;
                    ll ans = min({a1, a2, a3, a4});
                    if (ans >= MOD) cout << "impossible\n";
                    else cout << ans << '\n';
                }
            } else if (i < k && j >= k) {
                // case 3: on different sides of line
                ll xt = qrx(0, m);
                ll ct = qrc(j, n);
                ll cb = qrc(1, i-1);
                ll a1 = qrc(i, j-1);
                ll a2 = cb + ct;
                ll a3 = qrc(i, k-1) + xt + ct;
                ll a4 = cb + xt + qrc(k, j-1);
                ll ans = min({a1, a2, a3, a4});
                if (ans >= MOD) cout << "impossible\n";
                else cout << ans << '\n';
            } else if (i < k && j < k) {
                // case 4.1: both right of line
                ll a1 = qrc(i, j-1);
                ll ct = qrc(1, i-1);
                ll a2 = ct + qrc(j, n);
                ll a3 = ct + qrx(0, m) + qrc(j, k-1);
                ll ans = min({a1, a2, a3});
                if (ans >= MOD) cout << "impossible\n";
                else cout << ans << '\n';
            } else {
                // case 4.2: both left of line
                ll a1 = qrc(i, j-1);
                ll ct = qrc(j, n);
                ll a2 = ct + qrc(1, i-1);
                ll a3 = ct + qrx(0, m) + qrc(k, i-1);
                ll ans = min({a1, a2, a3});
                if (ans >= MOD) cout << "impossible\n";
                else cout << ans << '\n';
            }
        }
    }

}