#include<bits/stdc++.h>
#define int long long
#define rep(i, j, k) for(int i = j; i <= k; ++ i)
using namespace std;
const int N = 2e6 + 10;
int sum[N], sum2[N];
struct BST{
        int tr[N << 1], tot;
        void init(int siz){
            // memset(tr, 0, sizeof tr);
            tot = siz;
        }
        void add(int x, int num){
                while(x <= tot){
                        tr[x] += num;
                        x += x & (-x);
                }
        }
        int query(int x){
                int ans = 0;
                while(x){
                        ans += tr[x];
                        x -= x & (-x);
                }
                return ans;
        }
}Tr1, Tr2;
int n, m, k, q;
int dist(int u, int v){
	int ans = 1e14; 
	if(u == v) return 0;
	if(u > v) swap(u, v);
	int x = u, y = v, z = u + n;
	// cerr << u << " " << v << endl;
	if(!(Tr1.query(y - 1) - Tr1.query(x - 1))) ans = min(ans, sum[v - 1] - sum[u - 1]);
	if(!(Tr1.query(z - 1) - Tr1.query(y - 1))) ans = min(ans, sum[z - 1] - sum[y - 1]);
	// cout << ans << endl;
	return ans;
}
void solve(){
	cin >> n >> k >> m >> q;
	vector<int> a(n + 1), b(m + 100);
	vector<int> c(2 * n + 10);
	vector<int> d(m + 10);
	rep(i, 1, n) cin >> a[i];
	rep(i, 0, m) cin >> b[i];
	rep(i, 1, n) sum[i] = sum[i - 1] + a[i], c[i] = 1;
	rep(i, n + 1, 2 * n) sum[i] = sum[i - 1] + a[i - n], c[i] = 1;
	// cout << sum[2 * n] << endl;
	rep(i, 1, m + 1) sum2[i] = sum2[i - 1] + b[i - 1], d[i - 1] = 1;
	Tr1.init(2 * n); Tr2.init(m + 1);
	while(q--){
		char ch;
		cin >> ch;
		if(ch == 'c'){
			int cur; cin >> cur;
			// cerr <<  "c " << c[cur] << endl;
			Tr1.add(cur, c[cur]);
			Tr1.add(cur + n, c[cur + n]);
			c[cur] *= -1;
			c[cur + n] *= -1;
			continue;
		}
		if(ch == 'x'){
			int cur; cin >> cur;
			Tr2.add(cur + 1, d[cur]);
			// cerr << "x " << cur << " "<< d[cur] << endl;
			d[cur] *= -1;
		}
		if(ch == 'q'){
			int u, v;
			cin >> u >> v;
			if(u > v) swap(u, v);
			// int dit = dist(u, v);
			if(v <= n){
				int ans = dist(u, v);
				// cerr << q << " "<<ans << endl;
				// cerr << Tr1.query(7) << endl;
				// cerr << Tr1.query(3) << endl;
				if(!Tr2.query(m + 1)){
					int tt = sum2[m + 1];
					int d1 = dist(u, 1), d2 = dist(v, k);
					// cerr << d1 << " " << d2 << endl;
					ans = min(ans, d1 + d2 + tt);
					d1 = dist(u, k), d2 = dist(v, 1);
					ans = min(ans, d1 + d2 + tt);
				}
				if(ans == 1e14) cout << "impossible" << endl;
				else cout << ans << endl;
			}else if(u > n){
				int ans = 1e14;
				if(!(Tr2.query(v) - Tr2.query(u))) ans = sum2[v] - sum2[u];
				if(!Tr2.query(u) && !(Tr2.query(m + 1) - Tr2.query(v))){
					ans = min(ans, dist(1, k) + sum2[u] + sum2[m + 1] - sum2[v]);
				}
				if(ans == 1e14) cout << "impossible" << endl;
				else cout << ans << endl;
			}else{
				int ans = 1e14;
				if(!Tr2.query(v)){
					ans = min(ans, sum2[v] + dist(1, u));
				}
				if(!(Tr2.query(m + 1) - Tr2.query(v))){
					ans = min(ans, sum2[m + 1] - sum2[v] + dist(k, u));
				}
				if(ans == 1e14) cout << "impossible" << endl;
				else cout << ans << endl;
			}
		}
	}
}
signed main(){
	ios::sync_with_stdio(0);
	int T = 1;
	// cin >> T;
	while(T--) solve();
}