#include <bits/stdc++.h>

using namespace std;

#define int long long

const int N = 2e6 + 5;
const int inf = 4e8 + 5;

int toggle[N], w[N];
int n, m, k, q;

int bit[N];
void upd(int x, int val) {
  for (; x <= n + m + 1; x += x & (-x)) bit[x] += val;
}
int qry(int x) {
  int res = 0;
  for (; x; x -= x & (-x)) res += bit[x];
  return res;
}
int sum(int l, int r) {
  return qry(r) - qry(l - 1);
}

int dis(int x, int y) {
  int res = inf;
  if (x > y) swap(x, y);
  if (x <= n && y <= n) res = min({res, sum(x, y - 1), sum(1, n) - sum(x, y - 1)});
  if ((x == 1 || x == k || x > n) && (y == 1 || y == k || y > n)) {
    if (x == 1) x = n;
    else if (x == k) x = n + m + 1;
    if (y == 1) y = n;
    else if (y == k) y = n + m + 1;
    if (x > y) swap(x, y);
    res = min(res, sum(x + 1, y));
  }
  return res;
}

void solve() {
  cin >> n >> k >> m >> q;
  for (int i = 1; i <= n + m + 1; ++i) {
    cin >> w[i];
    upd(i, w[i]);
  }
  int x, y;
  char op;
  while (q--) {
    cin >> op >> x;
    if (op == 'q') {
      cin >> y;
      int res = dis(x, y);
      for (int i = 1; i <= k; i += k - 1) {
        for (int j = 1; j <= k; j += k - 1) {
          res = min(res, dis(x, i) + dis(y, j) + dis(i, j));
        }
      }
      if (res == inf) cout << "impossible\n";
      else cout << res << "\n";
    } else {
      if (op == 'x') x += n + 1;
      if (toggle[x]) upd(x, w[x] - inf);
      else upd(x, inf - w[x]);
      toggle[x] ^= 1;
    }
  }
}

signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int T = 1;
  // cin >> T;
  while (T--) solve();
}