#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define int ll
#define ff first
#define ss second
#define pb push_back
#define eb emplace_back
#define mkp make_pair
typedef pair<int, int> pii;
const int inf=INT_MAX;
const int maxn=1e6+10;

int n, m, k, q;
int a[maxn];
int tree[4*maxn];
void build(int node=0, int l=1, int r=n+m+1){
    if(l==r){
        tree[node]=a[l];
        return;
    }
    int mid = (l+r)/2;
    build(2*node+1,l,mid);
    build(2*node+2,mid+1,r);
    if(tree[2*node+1]==inf)
        tree[node]=inf;
    else if(tree[2*node+2]==inf)
        tree[node]=inf;
    else
        tree[node] = tree[2*node+1] + tree[2*node+2];
}
void update(int idx, int v, int node=0, int tl=1, int tr=n+m+1){
    if(tl==tr){
        tree[node]=v;
        return;
    }
    int mid = (tl+tr)/2;
    if(tl<=idx and idx<=mid) update(idx,v,2*node+1,tl,mid);
    else update(idx,v,2*node+2,mid+1,tr);
    if(tree[2*node+1]==inf)
        tree[node]=inf;
    else if(tree[2*node+2]==inf)
        tree[node]=inf;
    else
        tree[node] = tree[2*node+1] + tree[2*node+2];
}
int query(int l, int r, int node=0, int tl=1, int tr=n+m+1){
    if(r<tl or l>tr) return 0;
    if(l<=tl and r>=tr) return tree[node];
    int mid = (tl+tr)/2;
    if(query(l, r, 2*node+1, tl, mid)==inf)
        return inf;
    else if(query(l, r, 2*node+2, mid+1, tr)==inf)
        return inf;
    else 
        return query(l, r, 2*node+1, tl, mid) + query(l, r, 2*node+2, mid+1, tr);
}

int p11(int v)
{
    if(v==1)
        return 0;
    if(v>n)
        return query(n+1, v);
    return query(1, v-1);
}
int p12(int v)
{
    if(v==1)
        return 0;
    if(v>n)
        return query(n+1, v);
    return query(v, n);
}
int pk1(int v)
{
    if(v==k)
        return 0;
    if(v>n)
        return query(v+1, n+m+1);
    if(v<k)
        return min(inf, query(k, n)+query(1, v-1));
    // if(v>=k)
        return query(k, v-1);
}
int pk2(int v)
{
    if(v==k)
        return 0;
    if(v>n)
        return query(v+1, n+m+1);
    if(v<k)
        return query(v, k-1);
    // if(v>=k)
        return min(inf, query(1, k-1)+query(v, n));
}

int32_t main()
{
    #ifndef ONLINE_JUDGE
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout); 
    #endif
    ios::sync_with_stdio(0);cin.tie(0);

    cin>> n>> k>> m>> q;
    for(int i=1; i<=n+m+1; i++)
        cin>> a[i];
    int sc=0, sx=0;
    for(int i=1; i<=n; i++)
        sc+=a[i];
    for(int i=n+1; i<=n+m+1; i++)
        sx+=a[i];
    build();
    while(q--)
    {
        char c; cin>> c;
        if(c=='q')
        {
            int u, v; cin>> u>> v;
            if(u>v)
                swap(u, v);
            int mn=inf;
            if(u<=n && v<=n)
            {
                mn=min(mn, query(u, v-1));
                if(query(u, v)!=inf)
                    mn=min(mn, sc-query(u, v-1));
            }
            else if(u>n && v>n)
            {
                mn=min(mn, query(u+1, v));
                if(query(u, v)!=inf)
                    mn=min(mn, sx-query(u+1, v));
            }
            mn=min(mn, p11(u)+p11(v));
            mn=min(mn, p11(u)+p12(v));
            mn=min(mn, p12(u)+p11(v));
            mn=min(mn, p12(u)+p12(v));
            mn=min(mn, pk1(u)+pk1(v));
            mn=min(mn, pk1(u)+pk2(v));
            mn=min(mn, pk2(u)+pk1(v));
            mn=min(mn, pk2(u)+pk2(v));
            mn=min(mn, p11(u)+query(n+1, n+m+1)+pk1(v));
            mn=min(mn, p11(u)+query(n+1, n+m+1)+pk2(v));
            mn=min(mn, p12(u)+query(n+1, n+m+1)+pk1(v));
            mn=min(mn, p12(u)+query(n+1, n+m+1)+pk2(v));
            mn=min(mn, pk1(u)+query(n+1, n+m+1)+p11(v));
            mn=min(mn, pk1(u)+query(n+1, n+m+1)+p12(v));
            mn=min(mn, pk2(u)+query(n+1, n+m+1)+p11(v));
            mn=min(mn, pk2(u)+query(n+1, n+m+1)+p12(v));
            if(mn==inf)
            {
                cout<< "impossible\n";
                continue;
            }
            cout<< mn<< "\n";
        }
        else if(c=='c')
        {
            int i; cin>> i;
            int cara=query(i, i);
            if(cara==inf)
                update(i, a[i]);
            else
                update(i, inf);
        }
        else if(c=='x')
        {
            int j; cin>> j;
            j+=n+1;
            int cara=query(j, j);
            if(cara==inf)
                update(j, a[j]);
            else
                update(j, inf);
        }
    }
 
    return 0;
}