#include <iostream> #include <set> using namespace std; const int N = 1e6+10; int p[N]; int find(int x){ if(x != p[x]) p[x] = find(p[x]); return p[x]; } int main(){ int a, b; set<int> s, cnt; for(int i = 1; i <= N; i ++) p[i] = i; while(cin>>a>>b){ p[find(a)] = find(b); cnt.insert(a); cnt.insert(b); } for(auto i : cnt){ s.insert(find(i)); } cout<<s.size(); return 0; }