W = int(input())
H = int(input())
N = int(input())

Suites = [H] * W
Numbers = [W] * H

Hand_Suite_Set = set()
Hand_Number_Set = set()
Cards = set()
for i in range(N):
    s, n = map(int, input().split())
    s, n = s - 1, n - 1
    Suites[s] -= 1
    Numbers[n] -= 1
    Hand_Suite_Set.add(s)
    Hand_Number_Set.add(n)
    Cards.add((s, n))

ans = 0
for s in Hand_Suite_Set:
    ans += Suites[s]
for n in Hand_Number_Set:
    ans += Numbers[n]

for s in Hand_Suite_Set:
    for n in Hand_Number_Set:
        if (s, n) in Cards:
            continue
        ans -= 1

print(ans)