#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#define fo(i,a,b) for(i=a;i<=b;i++)
using namespace std;
const int maxn=2000007;
int i,j,k,t,n,m,ans;
int a[maxn],now,cas,x,y,num,p,q;
int l[maxn],r[maxn],qian[maxn],mx[maxn],xu[maxn],hao[maxn];
char s[10];
void doing(int now){
if(now==maxn)return;
qian[now]=qian[l[now]]+a[now];
mx[now]=max(mx[l[now]],qian[now]);
hao[now]=hao[l[now]]+1;
xu[hao[now]]=mx[now];
}
int main(){
// freopen("fan.in","r",stdin);
// freopen("fan.out","w",stdout);
l[0]=-1;r[0]=maxn;
mx[0]=-0x7fffffff;
memset(mx,128,sizeof(mx));
for(scanf("%d",&cas);cas;cas--){
scanf("%s",s);
if(s[0]=='I'){
scanf("%d",&k);
a[++num]=k;p=now,q=r[now];
l[num]=p,r[p]=num,l[q]=num,r[num]=q;
now=num;
doing(now);
}
else if(s[0]=='D'){
p=l[now],q=r[now];
r[p]=q,l[q]=p;
if(p==-1)now=q;else now=p;
doing(r[now]);
}
else if(s[0]=='L'){
if(l[now]!=-1)now=l[now];
}
else if(s[0]=='R'){
if(r[now]==maxn)continue;
if(r[now]!=maxn)now=r[now];
doing(now);
}
else if(s[0]=='Q'){
scanf("%d",&k);
printf("%d\n",xu[k]);
}
}
}