#include <iostream>
//#include "grader.h"
using namespace std;
#define S second
#define F first
#define LL long long
const int N = 1e6+1;
const LL MOD = 1e9+7;
const LL LINF = 1e18;
const LL INF = 1e9;
char s[N];
int par[21][N],len[N];
int cnt = 1;
char last;
void Init() {}
void buildst(int x,int pr){
par[0][x] = pr;
len[x] = len[pr];
int cur = pr;
for(int i=1;i<=20;i++)
par[i][x] = par[i-1][cur],cur = par[i-1][cur];
}
void TypeLetter(char L) {
buildst(cnt,cnt-1);
len[cnt]++;
s[cnt] = L;
cnt++;
}
void UndoCommands(int U) {
buildst(cnt,cnt-U-1);
cnt++;
}
char GetLetter(int P) {
cnt--;
P++;
int cur = cnt;
for(int i=20;i>=0;i--)
if(len[par[i][cur]]>=P)cur = par[i][cur];
cnt++;
return s[cur];
}
