def increment(dic, key):
    if key in dic:
        dic[key] += 1
    else:
        dic[key] = 1

w = input()
h = input()
n = input()

hor = {}
ver = {}

for i in xrange(n):
    x, y = map(int, raw_input().split())
    increment(hor, y)
    increment(ver, x)

ans = 0
for num in hor.itervalues():
    ans += w - num

for num in ver.itervalues():
    ans += h - len(hor)

print ans