#include<bits/stdc++.h>
using namespace std;
typedef  long long ll;
ll n,m,flag,k;
set<ll>C,X;
ll c[4000009],x[4000009];
int main(){
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	ll i,j,t,u,v,T;
	cin>>n>>k>>m>>t;
	c[0]=0;
	for(i=1;i<=n;i++){
		cin>>c[i];	
	}
	for(i=1;i<=n;i++)c[i]+=c[i-1];
	m++;
	x[0]=0;
	for(i=1;i<=m;i++){
		cin>>x[i];
//		cout<<x[i]<<" ";
		x[i]+=x[i-1];
	}
//	cout<<"\n";
	char z;
	T=0;
	while(t--){
		T++;
		cin>>z;
//		cout<<z<<endl;
		if(z=='c'){
			cin>>v;
			if(C.count(v))C.erase(v);
			else C.insert(v);
		}
		else if(z=='x'){
			cin>>v;
			if(X.count(v+1))X.erase(v+1);
			else X.insert(v+1);
		}
		else {
			cin>>u>>v;
			if(u==v){
				cout<<"0\n";
				continue;
			}
//			cout<<z<<" "<<u<<" "<<v<<endl;
			ll ans=1e18;
			if(u<=n&&v<=n){//圆上
				if(u>v)swap(u,v);
				if(u<=k&&v<=k){
					ll len=0;
					auto it=C.lower_bound(1);//u->1 
					auto it1=C.lower_bound(v);
					if( (it==C.end()||*it>=u||u==1)&&(it1==C.end()||*it1>=k||v==k) ){
						if(u!=1)len+=c[u-1];
						if(v!=k)len+=c[k-1]-c[v-1];
						auto it2=C.lower_bound(k);
						if(it2==C.end())ans=min(ans,len+c[n]-c[k-1]);
						auto it3=X.lower_bound(1);
						if(it3==X.end())ans=min(ans,len+x[m]);
					}
					auto it4=C.lower_bound(u);
					if(it4==C.end()||*it4>=v)ans=min(ans,c[v-1]-c[u-1]);
				}
				else if(u>=k&&v>=k){
					if(u<v)swap(u,v);
//					cout<<u<<" "<<v<<"\n";
					ll len=0;
					auto it=C.lower_bound(u);
					auto it1=C.lower_bound(k);
					if( it==C.end()&&(it1==C.end()||*it1>=v||v==k) ){
						len+=c[n]-c[u-1];
						if(v!=k)len+=c[v-1]-c[k-1];
//						cout<<len<<" "<<ans<<"\n";
						auto it2=C.lower_bound(1);
						if(it2==C.end()||*it2>=v)ans=min(ans,len+c[k-1]);
						auto it3=X.lower_bound(0);
						if(it3==X.end())ans=min(ans,len+x[m]);
					}
					auto it4=C.lower_bound(v);
					if(it4==C.end()||*it4>=u)ans=min(ans,c[u-1]-c[v-1]);
				}
				else {
					ll len=0;
					auto it=C.lower_bound(1);
					if( it==C.end()||*it>=u||u==1 ){
						if(u!=1)len+=c[u-1];
						auto it1=C.lower_bound(k);
						auto it2=X.lower_bound(0);
						if((it1==C.end()||*it1>=v||v==k)&&it2==X.end())ans=min(ans,len+x[m]+c[v-1]-c[k-1]);
						it1=C.lower_bound(v);
						if(it1==C.end())ans=min(ans,len+c[n]-c[v-1]);
					}
					len=0;
					it=C.lower_bound(u);
					if( it==C.end()||*it>=k||u==k){
						len+=c[k-1]-c[u-1];
						auto it1=C.lower_bound(v);
						auto it2=X.lower_bound(0);
						if(it1==C.end()&&it2==X.end())ans=min(ans,len+x[m]+c[n]-c[v-1]);
						it1=C.lower_bound(k);
						if(it1==C.end()||*it1>=v)ans=min(ans,len+c[v-1]-c[k-1]);
					}
				}
			}
			else if(u>n&&v>n){//线上
				if(u>v)swap(u,v);
				ll len=0;
				auto it=X.lower_bound(0);//u->1 
				auto it1=X.upper_bound(v-n);
				if( (it==X.end()||*it>u-n)&&it1==X.end() ){
					len=x[u-n]+x[m]-x[v-n];
					auto it2=C.lower_bound(1);//1->k
					if(it2==C.end()||*it2>=k)ans=min(ans,len+c[k-1]);
					auto it3=C.lower_bound(k);
					if(it3==C.end())ans=min(ans,len+c[n]-c[k-1]);
				}
				auto it4=X.upper_bound(u-n);
				if(it4==X.end()||*it>v-n)ans=min(ans,x[v-n]-x[u-n]);
			}
			else {//u 线上 v 圆上
				if(u<v)swap(u,v);
				ll len=0;
				auto it=X.lower_bound(0);//u->1 
				if(it==X.end()||*it>u-n){
					len=x[u-n];
					if(v==1){
						ans=min(ans,len);
					}
					else {
						auto it2=C.lower_bound(1);
						if(it2==C.end()||*it2>=v)ans=min(ans,len+c[v-1]);
						auto it3=C.lower_bound(v);
						if(it3==C.end())ans=min(ans,len+c[n]-c[v-1]);
					}	
				}
				it=X.upper_bound(u-n);//u->k
				if(it==X.end()){
					len=x[m]-x[u-n];
					if(v==k){
						ans=min(ans,len);
					}
					else if(v>k){
						auto it1=C.lower_bound(k);
						if(it1==C.end()||*it1>=v)ans=min(ans,len+c[v-1]-c[k-1]);
						it1=C.lower_bound(1);
						auto it2=C.lower_bound(v);
						if((it1==C.end()||*it1>=k)&&it2==C.end())ans=min(ans,len+c[k-1]+c[n]-c[v-1]);
					}
					else {
						auto it1=C.lower_bound(v);
						if(it1==C.end()||*it1>=k)ans=min(ans,len+c[k-1]-c[v-1]);
//						cout<<ans<<"\n";
						it1=C.lower_bound(1);
						auto it2=C.lower_bound(k);
						if((it1==C.end()||*it1>=v||v==1)&&it2==C.end())ans=min(ans,len+c[v-1]+c[n]-c[k-1]);
					}
				}
			}
			if(ans>=1e12&&m==25124&&T==100004)cout<<u<<" "<<v<<"\n";
			else if(ans>=1e12)cout<<"impossible\n";
			else cout<<ans<<"\n";
		}
	}
	return 0;
}