int main()
{
freopen("Text/ORDERSET.txt","r",stdin);
int Q; scanf("%d",&Q);
Treap oTreap;
while(Q--)
{
char t[5];
int p;
scanf("%s%d",t,&p);
if(t[0]=='I')
{
oTreap.Insert(p);
}
else if(t[0]=='D')
{
oTreap.Delete(p);
}
else if(t[0]=='K')
{
int v = oTreap.FindKth(p);
if(v > -INF)
{
printf("%d\n",v);
}
else
puts("invalid");
}
else
{
int v = oTreap.Count(p);
printf("%d\n",v);
}
}
return 0;
}
void solve(){
int N,X;
char ch[5];
scanf("%d",&N);
Treap root;
while(N--){
scanf("%s%d",ch,&X);
if (ch[0] == 'I')
root.Insert_unq(X);//, root.print();
else if (ch[0] == 'D')
root.Erase(X);
else if (ch[0] == 'C'){
int res = root.Count(X);
printf("%d\n",res);
} else {
int res = root.Kth(X);
if (res == INT_MIN)
printf("invalid\n");
else
printf("%d\n",res);
}
}
}