#include <iostream>
#include <algorithm>
#include <math.h>
#include <unordered_map>
#include <queue>
#include <vector>
#include <cstring>
using namespace std;
typedef long long ll;
#define x first
#define y second
#define int long long
#define endl '\n'
typedef pair<int,int> PII;
const int N = 1e6 + 10,mod = 998244353,M = 2 * N,INF = 1e9;
int c[N],x[N],tr[N * 2];
int T,n,k,m,q;

int lowbit(int x){
	return x & -x;
}

void modify(int x,int c){
	for(int i = x;i <= n + m;i += lowbit(i)) tr[i] += c;
}

int query(int x){
	int res = 0;
	for(int i = x;i;i -= lowbit(i)) res += tr[i];
	return res;
}

void solve()
{
	cin >> n >> k >> m >> q;
	m++;
	for(int i = 1;i <= n;i++) cin >> c[i],modify(i,c[i]);
	for(int i = 1;i <= m;i++) cin >> x[i],modify(n + i,x[i]);
	while(q--)
	{
		char op[2];
		cin >> op;
		if(*op == 'q'){
			int u,v;
			cin >> u >> v;
			if(u > v) swap(u,v);
			int tmp1,tmp2,tmp3;
			if(v <= n){
				tmp1 = query(v - 1) - query(u - 1);
				tmp2 = query(n) - tmp1;
				tmp3 = 0;
				if(u <= k && v <= k){
					tmp3 = query(n + m) - query(n) + query(u - 1) + query(k - 1) - query(v - 1);
				}
				else if(v > k && u <= k){
					tmp3 = query(n + m) - query(n) + query(u - 1) + query(v - 1) - query(k - 1);
					tmp3 = min(tmp3,query(n + m) - query(v - 1) + query(k - 1) - query(u - 1));
				}
				else{
					tmp3 = query(n + m) - query(v - 1) + query(u - 1) - query(k - 1);
				}
			}
			else if(u <= n && v > n){
				if(u <= k){
					tmp1 = query(n + m) - query(v) + query(k - 1) - query(u - 1);
					tmp2 = query(v) - query(n) + query(u - 1);
					tmp3 = query(v) - query(u - 1);
				}
				else{
					tmp1 = query(v) - query(u - 1);
					tmp2 = query(n + m) - query(v) + query(u - 1) - query(k - 1);
					tmp3 = query(u - 1) + query(v) - query(n);
				}
			}
			else{
				tmp1 = query(v) - query(u);
				tmp2 = query(n + m) - query(v) + query(u) - query(k - 1);
				tmp3 = query(n + m) - query(v) + query(u) - query(n) + query(k - 1);
			}
			int ans = min(tmp1,min(tmp2,tmp3));
			if(ans >= INF) cout << "impossible" << endl;
			else cout << ans << endl;
		}
		else if(*op == 'c'){
			int num;
			cin >> num;
			if(c[num] >= INF) modify(num,-INF),c[num] -= INF;
			else modify(num,INF),c[num] += INF;
		}
		else{
			int num;
			cin >> num;
			num++;
			if(x[num] >= INF) modify(num + n,-INF),x[num] -= INF;
			else modify(num + n,INF),x[num] += INF;
		}
	}
}

signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	T = 1;
	while(T--)
	{
		solve();
	}	
}