from collections import Counter
class UnionFind():
	def __init__(self,n):
		self.parents = list(range(n))

	def find(self, x):
		if self.parents[x] == x:
			return x
		else:
			self.parents[x] = self.find(self.parents[x])
			return self.parents[x]
	
	def union(self, x, y):
		px = self.find(x)
		py = self.find(y)
		if px != py:
			self.parents[px] = py

def main():
	n,m=map(int,input().split())
	uf = UnionFind(2*n+1)
	for i in range(m):
		a,b=map(int,input().split())
		uf.union(a,b)
	p = [uf.find(x) for x in range(2*n+1)]
	c = Counter(p[1:])
	ans = 0
	for v in c.values():
		if v % 2 == 1:
			ans += 1
	
	print(ans//2)

if __name__ == "__main__":
	main()