#include<iostream>

using namespace std;

const int N=100010;

int a[N],n[N];
int head=-1;
int sum=0;

int main()
{
    int m,k,c,l;
    cin>>m;
    char x;
    while(m--)
    {
        cin>>x;
        if(x=='H')
        {
            cin>>c;
            sum++;
            a[sum]=c;
            n[sum]=head;
            head=sum;
        }
        else if(x=='D')
        {
            cin>>c;
            if(c==0)head=n[head];
            else
            n[c]=n[n[c]];

        }
        else if(x=='I')
        {
            cin>>k>>c;
            sum++;
            a[sum]=c;
            n[sum]=n[k];
            n[k]=sum;

        }
    }
    int i;
    for(i=head;i!=-1;i=n[i])
    cout<<a[i]<<' ';
    cout<<endl;
    return 0;
 }