This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std; 
typedef long long ll;
#define pb push_back
#define F first
#define S second
#define enter cout<<'\n';
#define INF 99999999999999999
#define MOD 1000000007
#define all(x) x.begin(),x.end()
char last;
ll idx=-1;
string s;
vector<pair<string,string>>v;
void Init() 
{
}
void TypeLetter(char L) {
  
  pair<string,string>curr;
  curr.F=s;
  s+=L;
  curr.S=s;
  v.pb(curr);
}
void UndoCommands(int U) {
  pair<string,string>curr;
  curr.F=s;
  curr.S=v[v.size()-U].F;
  v.pb(curr);
  s=curr.S;
}
char GetLetter(int P) {
  return s[P];
}
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