#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(v) v.begin(),v.end()
typedef long long ll;

#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;

int indeg[200200],rdeg[200200];
vector<int> G[200200];
int seen[200200];

template <typename T>
vector<T> compress(vector<T> &X){
  vector<T> vals=X;
  sort(vals.begin(),vals.end());
  vals.erase(unique(vals.begin(), vals.end()),vals.end());
  for(int i=0;i<(int)X.size(); i++){
    X[i]=lower_bound(vals.begin(),vals.end(),X[i])-vals.begin();
  }
  return vals;
}

void dfs(int v){
  seen[v]=1;
  for(auto nv:G[v]){
    if(seen[nv]) continue;
    dfs(nv);
  }
}
 
int main(){
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  
  int n;
  cin>>n;
  
  vector<int> A(2*n);
  rep(i,2*n) cin>>A[i];
  compress(A);
  vector<int> H(n),W(n);
  int manum=0;
  rep(i,n){
    H[i]=A[2*i],W[i]=A[2*i+1];
    manum=max({manum,H[i],W[i]});
  }

  scc_graph g(manum+1);
  rep(i,n){
    g.add_edge(H[i],W[i]);
    rdeg[H[i]]++;
    indeg[W[i]]++;
    G[H[i]].push_back(W[i]);
  }

  auto scc=g.scc();
  int cnt=0;
  rep(i,n){
    if((rdeg[i]+indeg[i])%2==1) cnt++;
  }
  
  if(scc.size()==1){
    if(cnt==0) cout<<manum+1<<endl;
    else if(cnt==2) cout<<1<<endl;
    else cout<<0<<endl;
  }
  else{
    int s=scc[0][0];
    dfs(s);
    bool b=true;
    rep(i,manum+1){
      if(seen[i]==0 || abs(indeg[i]-rdeg[i])>1) b=false;
    }
    if(b) cout<<1<<endl;
    else cout<<0<<endl;
  }
    
  return 0;
}