import sys

input=sys.stdin.readline
N,M,Q=map(int,input().split())
E=[[0]*(M+1) for _ in range(N+1)]

for _ in range(Q):
    a,b=map(int,input().split())
    E[a][b]=1

DP=[[0]*(M+1) for _ in range(N+1)]
for i in range(1,N+1):
    D=DP[i]; DD=DP[i-1]
    e=E[i]
    for j in range(1,M+1):
        if e[j]==0:
            D[j]=max(D[j-1], DD[j])
        else:
            D[j]=max(D[j-1], DD[j], DD[j-1]+1)

print(DP[N][M])