n,m,q=map(int,input().split())
check=[[0]*m for i in range(n)]
for i in range(q):
  a,b=map(int,input().split())
  check[a-1][b-1]=1
d=[[0]*(m+1) for i in range(n+1)]
for i in range(1,n+1):
  for j in range(1,m+1):
    if check[i-1][j-1]:
      d[i][j]=d[i-1][j-1]+1
    else:
      d[i][j]=max(d[i-1][j],d[i][j-1])
print(d[n][m])