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 unite(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 same(self,x,y):
        return self.find(x)==self.find(y)

    def size(self,x):
        return -self.parents[self.find(x)]

    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 groups(self):
        group=[[] for _ in range(self.n)]
        for i in range(self.n):
            group[self.find(i)].append(i)
        return [g for g in group if g]


import sys
input=sys.stdin.readline
n,m=map(int,input().split())
max_lst=[0]*n
uf=UnionFind(n)
bc=sorted([tuple(map(int,input().split())) for _ in range(n)],key=lambda x:(x[1],x[0]))
for i in range(1,n):
    if bc[i-1]==bc[i]:
            uf.unite(i-1,i)
for i in range(n):
    s=uf.size(i)
    max_lst[bc[i][1]-1]=max(max_lst[bc[i][1]-1],s)
print(n-sum(max_lst))