w = int(input())
h = int(input())
n = int(input())
s, k = {i:0 for i in range(1, w + 1)}, {i:0 for i in range(1, h + 1)}
for i in range(n):
    te, mp = map(int, input().split())
    s[te] += 1
    k[mp] += 1
    
ans = 0
tmp = 0
for i in range(1, w + 1):
    if s[i] != 0:
        ans += h - s[i]
        tmp += 1

for i in range(1, h + 1):
    if k[i] != 0:
        ans += w - tmp

print(ans)