#include<bits/stdc++.h>
#define int long long
#define endl '\n'
#define IO ios::sync_with_stdio(0),cin.tie(0); 
using namespace std;
struct BIT{
    vector<int>bit;
    int n;
    void init(int nn){
        n=nn+1;
        bit=vector<int>(n,0);
    }
    int lowbit(int x){return x&-x;}
    int query(int x){
        int res=0;
        for(;x>0;x-=lowbit(x)){
            res+=bit[x];
        }
        return res;
    }
    void upd(int x,int v){
        for(;x<n;x+=lowbit(x)){
            bit[x]+=v;
        }
    }
}bit,ch;
bool broke[2000060];
bool check(int l,int r){
    if(l==1){
        return ch.query(r)==0;
    }else {
        return ch.query(r)-ch.query(l-1)==0;
    }
}
int qq(int l,int r){
    if(l==1){
        return bit.query(r);
    }else {
        return bit.query(r)-bit.query(l-1);
    }
}
signed main(){
    IO
    int n,k,m,q;
    cin>>n>>k>>m>>q;
    memset(broke,0,sizeof(broke));
    bit.init(n+m+1+5);
    ch.init(n+m+1+5);
    for(int i=1;i<=n;i++){
        int now;
        cin>>now;
        bit.upd(i,now);
    }
    for(int i=n+1;i<=n+m+1;i++){
        int now;
        cin>>now;
        bit.upd(i,now);
    }
    while(q--){
        char c;
        cin>>c;
        if(c=='q'){
            int x,y;
            cin>>x>>y;
            int ans=1e16;
            if(x>y)swap(x,y);
            if(x==1&&y==k){
                //right 1~k-1
                if(check(1,k-1)){
                    ans=min(ans,qq(1,k-1));
                }
                //straight 
                if(check(n+1,n+1+m)){
                    ans=min(ans,qq(n+1,n+1+m));
                }
                //left
                if(check(k,n)){
                    ans=min(ans,qq(k,n));
                }
            }else {
                int x1=1e16;//x->1
                int xk=1e16;//x->k
                int y1=1e16;//y->1
                int yk=1e16;//y->k
                int ok=1e16;//o->k 
                if(x==1){
                    x1=0;
                    if(check(1,k-1))xk=min(xk,qq(1,k-1));
                    if(check(k,n))xk=min(xk,qq(k,n));
                    if(check(n+1,n+m+1))xk=min(xk,qq(n+1,n+m+1));
                }else if(x==k){
                    xk=0;
                    if(check(1,k-1))x1=min(x1,qq(1,k-1));
                    if(check(k,n))x1=min(x1,qq(k,n));
                    if(check(n+1,n+m+1))x1=min(x1,qq(n+1,n+m+1));
                }else {
                    if(x>1&&x<k){
                        if(check(1,x-1))x1=min(x1,qq(1,x-1));
                        if(check(x,k-1))xk=min(xk,qq(x,k-1));
                    }else if(x<=n){
                        if(check(x,n))x1=min(x1,qq(x,n));
                        if(check(k,x-1))xk=min(xk,qq(k,x-1));
                    }else {
                        if(check(n+1,x))x1=min(x1,qq(n+1,x));
                        if(check(x+1,n+m+1))xk=min(xk,qq(x+1,n+m+1));
                    }
                }
                if(y==1){
                    y1=0;
                    if(check(1,k-1))yk=min(yk,qq(1,k-1));
                    if(check(k,n))yk=min(yk,qq(k,n));
                    if(check(n+1,n+m+1))yk=min(yk,qq(n+1,n+m+1));
                }else if(y==k){
                    yk=0;
                    if(check(1,k-1))y1=min(y1,qq(1,k-1));
                    if(check(k,n))y1=min(y1,qq(k,n));
                    if(check(n+1,n+m+1))y1=min(y1,qq(n+1,n+m+1));
                }else {
                    if(y>1&&y<k){
                        if(check(1,y-1))y1=min(y1,qq(1,y-1));
                        if(check(y,k-1))yk=min(yk,qq(y,k-1));
                    }else if(y<=n){
                        if(check(y,n))y1=min(y1,qq(y,n));
                        if(check(k,y-1))yk=min(yk,qq(k,y-1));
                    }else {
                        if(check(n+1,y))y1=min(y1,qq(n+1,y));
                        if(check(y+1,n+m+1))yk=min(yk,qq(y+1,n+m+1));
                    }
                }
                if(check(1,k-1))ok=min(ok,qq(1,k-1));
                if(check(k,n))ok=min(ok,qq(k,n));
                if(check(n+1,n+m+1))ok=min(ok,qq(n+1,n+m+1));
                ans=min(ans,x1+y1);
                ans=min(ans,xk+yk);
                ans=min(ans,x1+ok+yk);
                ans=min(ans,xk+ok+y1);
                if(1<x&&x<k&&y<1&&y<k){
                    if(check(x,y-1))ans=min(ans,qq(x,y-1));
                }
                else if(k<x&&x<=n&&k<y&&y<=n){
                    if(check(x,y-1))ans=min(ans,qq(x,y-1));
                }
                else if(n<x&&n<y){
                    if(check(x+1,y))ans=min(ans,qq(x+1,y));
                }
            }
            if(ans==1e16){
                cout<<"impossible"<<endl;
            }else cout<<ans<<endl;
        }else if(c=='x'){
            int now;
            cin>>now;
            now+=n+1;
            if(broke[now]){
                broke[now]=0;
                ch.upd(now,-1);
            }else {
                broke[now]=1;
                ch.upd(now,1);
            }
        }else if(c=='c'){
            int now;
            cin>>now;
            if(broke[now]){
                broke[now]=0;
                ch.upd(now,-1);
            }else {
                broke[now]=1;
                ch.upd(now,1);
            }
        }
    }

}