#include <bits/stdc++.h>
using namespace std;
#define int long long 
string no="impossible";
int n,k,m,q;
const int maxn=2e6+10;
vector<pair<int,int>> ve[maxn];
const int inf =1e18;
bool ok[maxn];
struct kkk{
    int x,len;
    bool operator<(kkk k1)const{
        return len>k1.len;
    }
};
int t1[maxn],t2[maxn];
struct Treearray{
    int c[1000010],n;
    void set_n(int _n){
        n=_n;
        for(int i=1;i<=n;i++)c[i]=0;
    }
    int lowbit(int x){
        return x&(-x);
    }
    void update(int i,int k){    //在i位置加上k
        while(i <= n){
            c[i] += k;
            i += lowbit(i);
        }
    }
    int getsum(int i){        //求A[1 - i]的和
        int res = 0;
        while(i > 0){
            res += c[i];
            i -= lowbit(i);
        }
        return res;
    }
};
Treearray tri1,tri2;
int sum1[maxn],sum2[maxn];
int dis[maxn];
void addedge(int x,int y,int w){
    // cout<<"x="<<x<<" y="<<y<<" w="<<w<<"\n";
    ve[x].emplace_back(y,w);
    ve[y].emplace_back(x,w);
}
signed main()
{
    ios::sync_with_stdio(false);cin.tie(0);
    cin>>n>>k>>m>>q;
    for(int i=1;i<=n;i++){
        int w;cin>>w;
        sum1[i]=w;
        sum1[i]+=sum1[i-1];
    }
    for(int i=1;i<=m+1;i++){
        int w;cin>>w;
        sum2[i]=w;
        sum2[i]+=sum2[i-1];
    }
    for(int i=1;i<=n+m;i++)dis[i]=inf;
    tri1.set_n(n);
    tri2.set_n(m+1);
    while(q--){
        char c;cin>>c;
        if(c=='q'){
            vector<int> in;
            int x,y;
            cin>>x>>y;
            in.push_back(1);
            in.push_back(k);
            in.push_back(x);
            in.push_back(y);
            if(x>y)swap(x,y);
            function<void(int)> w1 = [&](int x){
                if(x>1&&x<k){
                    if(tri1.getsum(x-1)==0){
                        addedge(1,x,sum1[x-1]);
                    }
                    if(tri1.getsum(k-1)-tri1.getsum(x-1)==0){
                        addedge(x,k,sum1[k-1]-sum1[x-1]);
                    }
                }
            };
            w1(x);w1(y);
            function<void(int)> w2 = [&](int x){
                if(x>k&&x<=n){
                    if(tri1.getsum(x-1)-tri1.getsum(k-1)==0){
                        addedge(k,x,sum1[x-1]-sum1[k-1]);
                    }
                    if(tri1.getsum(n)-tri1.getsum(x-1)==0){
                        addedge(x,1,sum1[n]-sum1[x-1]);
                    }
                }
            };
            w2(x);w2(y);
            function<void(int)> w3 = [&](int x){
                if(x>n&&x<=n+m){
                    if(tri2.getsum(x-n)==0){
                        addedge(1,x,sum2[x-n]);
                    }
                    if(tri2.getsum(m+1)-tri2.getsum(x-n)==0){
                        addedge(x,k,sum2[m+1]-sum2[x-n]);
                    }
                }
            };
            w3(x);w3(y);
            if(((x>1&&x<k&&y>1&&y<k)||(x>k&&x<=n&&y>k&&y<=n))&&tri1.getsum(y-1)-tri1.getsum(x-1)==0){
                addedge(x,y,sum1[y-1]-sum1[x-1]);
            }
            if(x>n&&x<=n+m&&y>n&&y<=n+m&&tri2.getsum(y-n)-tri1.getsum(x-n)){
                addedge(x,y,sum2[y-n]-sum2[x-n]);
            }
            if(tri1.getsum(k-1)==0)addedge(1,k,sum1[k-1]);
            if(tri1.getsum(n)-tri1.getsum(k-1)==0)addedge(1,k,sum1[n]-sum1[k-1]);
            if(tri2.getsum(m+1)==0)addedge(1,k,sum2[m+1]);
            priority_queue<kkk,vector<kkk>> qu;
            qu.push(kkk{x,0});
            while(!qu.empty()){
                kkk k1=qu.top();qu.pop();
                // cout<<k1.x<<" "<<k1.len<<"\n";
                if(dis[k1.x]>k1.len){
                    dis[k1.x]=k1.len;
                }
                else continue;
                for(auto [to,len]:ve[k1.x])if(dis[to]==inf){
                    qu.push(kkk{to,len+k1.len});
                }
            }
            if(dis[y]==inf)cout<<no<<"\n";
            else cout<<dis[y]<<"\n";
            for(auto it:in){
                ve[it].clear();
                dis[it]=inf;
            }
        }
        if(c=='c'){
            int id;cin>>id;
            tri1.update(id,-t1[id]);
            t1[id]=1-t1[id];
            tri1.update(id,t1[id]);
        }
        if(c=='x'){
            int id;cin>>id;
            id++;
            tri2.update(id,-t2[id]);
            t2[id]=1-t2[id];
            tri2.update(id,t2[id]);
        }
    }
}