from collections import defaultdict 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): root = self.find(x) return [i for i in range(self.n) if self.find(i) == root] def roots(self): return [i for i, x in enumerate(self.parents) if x < 0] def group_count(self): return len(self.roots()) def group(self): group_members = defaultdict(list) for member in range(self.n): group_members[self.find(member)].append(member) return group_members def __str__(self): return ''.join(f'{r}: {m}' for r, m in self.group().items()) n,m = map(int,input().split()) uf = UnionFind(n) graph = [[] for i in range(n+1)] e=[] dout = defaultdict(int) din = defaultdict(int) for i in range(m): a,b = map(int,input().split()) a -= 1 b -= 1 graph[a].append(b) e.append([a,b]) uf.union(a,b) dout[b]+=1 din[a]+=1 d=defaultdict(list) cnt=-1 for i,l in uf.group().items(): if din[i] > 0: cnt+=1 for j in l: d[i].append(abs(din[j] - dout[j])) ans=0 for k,v in d.items(): s = max(sum(v)-1,0) ans += s//2 else: print(ans+cnt)