#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T L, T R) { while (L != R) cerr << *L << " \n"[next(L) == R], ++L; }
#else
#define DE(...) 0
#define debug(...) 0
#endif
const int MAX_N = 300005;
char last;
vector<vector<char>> res;
int curtime;
void Init() {
res.pb();
}
void TypeLetter(char L) {
res.pb(res.back());
res.back().pb(L);
++curtime;
}
void UndoCommands(int U) {
res.pb(res[curtime - U]);
++curtime;
}
char GetLetter(int P) {
return res.back()[P];
}
