w=int(input())
h=int(input())
n=int(input())
p=[]
for i in range(n):
    a,b=map(int,input().split())
    p.append([a,b])

cnt=[0]*w
for x in p:
    cnt[x[0]-1]+=1
y=max(cnt)
ans=0
for i in range(w):
    if cnt[i]>0:
        ans+=(h-cnt[i])
    elif cnt[i]==0:
        ans+=y

print(ans)