import sys
sys.setrecursionlimit(10 ** 8)

N,M = map(int,input().split())

parent = [-1] * (N + N)
def find(i):
    if parent[i] < 0:return i
    parent[i] = find(parent[i])
    return parent[i]
def unite(i,j):
    I = find(i)
    J = find(j)
    if I == J:return False
    if parent[I] < parent[J]:
        I,J =J,I
    parent[J] += parent[I]
    parent[I] = J
    return True

for _ in range(M):
    a,b = map(int,input().split())
    unite(a - 1,b - 1)
m = 0
for i in range(N + N):
    if parent[i] < 0:
        if -parent[i] > m:
            m = -parent[i]
if m <= N:
    print(N)
else:
    print(N + N - m)