#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define fi first
#define se second
#define all(v) v.begin(),v.end()
#define allarr(a) a , a + n
#define ll long long
#define ull unsigned long long
#define pb push_back
#define fastio ios_base::sync_with_stdio(false) ; cin.tie(NULL); cout.tie(NULL)
typedef pair<int, int> pi;
typedef pair<ll,ll> pll;
typedef pair<int,pi> trp ;
typedef vector<pi> vpi;
typedef vector<pll> vpll ;
// int ab (int x ) { return (x>0?x:-x); }
//
string s = "" ;
void Init(){
}
void UndoCommands(int U)
{
while( U && !s.empty() ){
s.pop_back();
U--;
}
}
void TypeLetter(char L){
s.pb(L);
}
char GetLetter(int P)
{
return s[P] ;
}
