# your code goes here
W=int(input())
H=int(input())
N=int(input())
S=[[int(i) for i in input ().split()] for i in range (N)]
T=[0]*W
L=[0]*H
for i in range (N):
 #   print (S)
    T[S[i][0]]+=1
    L[S[i][1]]+=1
C=0
for i in range (W):
#    print (T)
    if T[i]>0:
        C+=H-T[i]
for i in range (H):
    if L[i]>0:
        C+=W-L[i]
print (C)