from collections import defaultdict n,m=map(int,input().split()) lst=[[] for i in range(n)] for i in range(n): b,c=map(int,input().split()) b-=1 c-=1 lst[c].append(b) class UnionFind(): def __init__(self,n): self.n=n self.parents=[-1]*n def find(self,x): if self.parents[x]<0: return x else: self.parents[x]=self.find(self.parents[x]) return self.parents[x] def union(self,x,y): x=self.find(x) y=self.find(y) if x==y: return if self.parents[x]>self.parents[y]: x,y=y,x self.parents[x]+=self.parents[y] self.parents[y]=x def size(self,x): return -self.parents[self.find(x)] def same(self,x,y): return self.find(x)==self.find(y) def members(self,x): rood=self.find(x) return [i for i in range(self.n) if self.find(i)==root] def roots(self,x): return [i for i,x in enumerate(self.parents) if x<0] def group_count(self): return len(self.roots()) def all_group_members(self): groum_members=defaultdict(list) for member in range(self.n): group_members[self.find(member)].append(member) return group_members def __str__(self): return '\n'.join(f'{r}: {m}' for r, m in self.all_group_members().items()) slime=UnionFind(n) ans=0 for i in range(n): if len(lst[i])<2: continue for j in range(len(lst[i])): for k in range(j+1,len(lst[i])): if slime.same(lst[i][j],lst[i][k]): continue slime.union(lst[i][j],lst[i][k]) ans+=1 print(ans)