// IOI 2012 - Crayfish Scrivener
// Lúcio Cardoso
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e6+10;
const int MAXL = 22;
int t, pai, nivel[MAXN], k[MAXN], tab[MAXN][MAXL];
char C[MAXN];
void Init(void)
{
memset(tab, -1, sizeof tab);
}
void TypeLetter(char c)
{
t++;
k[t] = t, C[t] = c, nivel[t] = nivel[pai]+1;
tab[t][0] = pai;
for (int j = 1; j < MAXL; j++)
if (tab[t][j-1] != -1)
tab[t][j] = tab[tab[t][j-1]][j-1];
pai = t;
}
void UndoCommands(int u)
{
k[t+1] = k[t-u];
t++;
pai = k[t];
}
char GetLetter(int p)
{
if (p+1 == nivel[k[t]]) return C[k[t]];
int u = k[t];
p = nivel[k[t]]-p-1;
for (int i = MAXL-1; i >= 0; i--)
if (p-(1<<i) >= 0)
u = tab[u][i], p -= (1<<i);
return C[u];
}
