#int(input()) #map(int, input().split()) #list(map(int, input().split())) H, W, Q = map(int, input().split()) z = [0] * Q for i in range(Q): z[i] = list(map(int, input().split())) ans = H*W d = dict() for i in range(Q): y, x = z[i] if x not in d: ans -= H - y + 1 d[x] = y else: ans -= d[x] - min(d[x], y) d[x] = min(d[x], y) print(ans)