#include <cstdio>
#include <algorithm>
#include <cstring>
#include <iostream>
#include <vector>
#include <set>
#include <queue>
#include <map>
#include <ctime>
#include <random>
#include <cassert>
#include <numeric>
#include <cmath>
#include <bitset>
#include <ext/pb_ds/assoc_container.hpp>
#define pii pair<int, int>
#define fi first
#define se second
#define MP make_pair
#define ep emplace
#define eb emplace_back
//#define int long long
#define rep(i, j, k) for (int i = (j); i <= (k); i++)
#define per(i, j, k) for (int i = (j); i >= (k); i--)
typedef double db;
typedef long double ldb;
typedef long long ll;
//typedef __int128 lll;
typedef unsigned long long ull;
typedef unsigned int ui;
using namespace std;
using namespace __gnu_pbds;
bool Mbe;

//char buf[1<<20],*p1,*p2;
//#define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf,1,1<<20,stdin), p1 == p2) ? 0 : *p1++)
int read() {
	int s = 0, f = 1;
	char c = getchar();
	while (c < '0' || c > '9') f ^= (c == '-'), c = getchar();
	while (c >= '0' && c <= '9') s = s * 10 + c - '0', c = getchar();
	return f ? s : -s;
}
template<typename T>void chkmax(T&x,const T&y){if(x<y)x=y;}
template<typename T>void chkmin(T&x,const T&y){if(x>y)x=y;}

const int N=8005;
int n,cnt,a[N],id[N],stk[N],rk[N],top;
char op[10];
void Swap(int x,int y){
	id[a[x]]=y,id[a[y]]=x;
	swap(a[x],a[y]);
}
void add(int x){
	cnt++;
	a[cnt]=x,id[x]=cnt;
	int now=cnt;
	top=0;
	while(now){
		stk[++top]=now;
		if((now>>1)&&(now^1)<=cnt)stk[++top]=now^1;
		now>>=1;
	}
	printf("%d ",top);
	rep(i,1,top)printf("%d%c",a[stk[i]]," \n"[i==top]);
	fflush(stdout);
	rep(i,1,top)rk[read()]=i;
	now=cnt;
	while(now>1&&rk[a[now>>1]]>rk[a[now]]){
		Swap(now,now>>1);
		now>>=1;
		if((now<<1|1)<=cnt&&rk[a[now<<1]]>rk[a[now<<1|1]])Swap(now<<1,now<<1|1);
	}
}
void del(int x){
	if((id[x]<<1)>cnt)return cout<<0<<endl,cnt--,void();
	int pos=id[x];
	Swap(cnt,id[x]);
	cnt--;
	int now=pos;
	top=0;
	while(now<=cnt){
		stk[++top]=now;
		if((now<<1|1)<=cnt)stk[++top]=now<<1|1;
		now<<=1;
	}
	printf("%d ",top);
	rep(i,1,top)printf("%d%c",a[stk[i]]," \n"[i==top]);
	fflush(stdout);
	rep(i,1,top)rk[read()]=i;
	now=pos;
	while((now<<1)<=cnt&&rk[a[now<<1]]<rk[a[now]]){
		Swap(now,now<<1);
		if((now<<1|1)<=cnt&&rk[a[now<<1]]>rk[a[now<<1|1]])Swap(now<<1,now<<1|1);
		now<<=1;
	}
}

bool Med;
signed main() {
	fprintf(stderr,"%.3lfMb\n",(&Mbe-&Med)/1024./1024.);
	n=read();
	for(int T=n+n;T--;){
		scanf("%s",op);
		int x=read();
		if(op[0]=='a')add(x);
		else del(x);
		if(!cnt)printf("-1\n");
		else printf("%d\n",a[1]);
		fflush(stdout);
	}
	return 0;
}