H, W = list(map(int, input().split()))

if H==1 or W==1:

  print((1))

else:

  print(((H*W+1)//2))
import sys

def input(): return sys.stdin.readline().strip()

def mapint(): return list(map(int, input().split()))

sys.setrecursionlimit(10**9)



from math import ceil

H, W = mapint()

if H==1 or W==1:

    print((1))

else:

    print((ceil(H*W/2)))
H, W = list(map(int, input().split()))
if H == 1 or W == 1:
    print((1))
else:
    print(((H * W + 1) // 2))

import sys


def input():
    return sys.stdin.readline().strip()


def mapint():
    return list(map(int, input().split()))


sys.setrecursionlimit(10**9)
from math import ceil

H, W = mapint()
if H == 1 or W == 1:
    print((1))
else:
    print((ceil(H * W / 2)))

-H, W = list(map(int, input().split())) +import sys + + +def input(): +    return sys.stdin.readline().strip() + + +def mapint(): +    return list(map(int, input().split())) + + +sys.setrecursionlimit(10**9) +from math import ceil + +H, W = mapint() -    print(((H * W + 1) // 2)) +    print((ceil(H * W / 2)))