#include <bits/stdc++.h>

using namespace std;
ifstream f ("hashuri.in") ;
ofstream g ("hashuri.out") ;
unordered_set<int> s;
int n,t,x;
int main ()
{
    f>>n;
    for( ; n;n--)
        f>>t>>x;
  if(t==1)
        s.insert(x) ;
        else if(t==2)
            s.erase(x);
 else if (s.find(X) == s.end()) ;
    g<<"0/n";
else
    g<<"1/n";
    return 0;