import sys
input = sys.stdin.readline

class SegTree:
    """ define what you want to do with 0 index, ex) size = tree_size, func = min or max, sta = default_value """
    
    def __init__(self,size,func,sta):
        self.n = size
        self.size = 1 << size.bit_length()
        self.func = func
        self.sta = sta
        self.tree = [sta]*(2*self.size)

    def build(self, list):
        """ set list and update tree"""
        for i,x in enumerate(list,self.size):
            self.tree[i] = x

        for i in range(self.size-1,0,-1):
            self.tree[i] = self.func(self.tree[i<<1],self.tree[i<<1 | 1])

    def set(self,i,x):
        i += self.size
        self.tree[i] = x
        while i > 1:
            i >>= 1
            self.tree[i] = self.func(self.tree[i<<1],self.tree[i<<1 | 1])

    def pointget(self,x):
        return self.tree[x+self.size]

    def get(self,l,r):
        """ take the value of [l r) with func (min or max)"""
        l += self.size
        r += self.size
        res = self.sta

        while l < r:
            if l & 1:
                res = self.func(self.tree[l],res)
                l += 1
            if r & 1:
                res = self.func(self.tree[r-1],res)
            l >>= 1
            r >>= 1
        return res

n,m,q = map(int,input().split())
AB = [list(map(int,input().split())) for i in range(q)]
AB.sort(key=lambda x:(x[0],-x[1]))

def func(x,y):
    if x > y:
        return x
    return y

seg = SegTree(m+5,func,0)

for a,b in AB:
    now = seg.pointget(b)
    nex = seg.get(0,b)
    if now == nex+1:
        continue
    seg.set(b,nex+1)
print(seg.get(0,m+2))