#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<tuple<int,int,int>> ve[maxn];
bool ok[maxn];
struct kkk{
    int x,len;
    bool operator<(kkk k1)const{
        return len>k1.len;
    }
};
signed main()
{
    ios::sync_with_stdio(false);cin.tie(0);
    cin>>n>>k>>m>>q;
    for(int i=1;i<=n;i++){
        int x=i,y=i%n+1;
        int w;cin>>w;
        ve[x].emplace_back(y,w,i);
        ve[y].emplace_back(x,w,i);
    }
    for(int i=0;i<=m;i++){
        int x,y;
        int w;cin>>w;
        if(i==0){
            x=1,y=n+1;
        }
        else if(i==m){
            x=n+m,y=k;
        }
        else x=n+i,y=n+i+1;
        ve[x].emplace_back(y,w,i+n+1);
        ve[y].emplace_back(x,w,i+n+1);
    }
    while(q--){
        char c;cin>>c;
        if(c=='q'){
            int beg,ed;
            cin>>beg>>ed;
            int inf =1e18;
            vector<int> dis(n+m+1,inf);
            priority_queue<kkk,vector<kkk>> qu;
            qu.push(kkk{beg,0});
            while(!qu.empty()){
                kkk k1=qu.top();qu.pop();
                if(dis[k1.x]>k1.len){
                    dis[k1.x]=k1.len;
                }
                else continue;
                for(auto [to,l,id]:ve[k1.x])if(!ok[id]){
                    qu.push(kkk{to,k1.len+l});
                }
            }
            if(dis[ed]==inf)cout<<no<<"\n";
            else cout<<dis[ed]<<"\n";
        }
        if(c=='x'){
            int id;cin>>id;id+=n+1;
            ok[id]=!ok[id];
        }
        if(c=='c'){
            int id;cin>>id;
            ok[id]=!ok[id];
        }
    }
}