Problem:
 Score : 200 points    Problem Statement We have a board with H horizontal rows and W vertical columns of squares.
There is a bishop at the top-left square on this board.
How many squares can this bishop reach by zero or more movements?  Here the bishop can only move diagonally.
More formally, the bishop can move from the square at the r_1 -th row (from the top) and the c_1 -th column (from the left) to the square at the r_2 -th row and the c_2 -th column if and only if exactly one of the following holds:   r_1 + c_1 = r_2 + c_2  r_1 - c_1 = r_2 - c_2   For example, in the following figure, the bishop can move to any of the red squares in one move:       Constraints  1 \leq H, W \leq 10^9  All values in input are integers.         Input Input is given from Standard Input in the following format:  H \ W       Output Print the number of squares the bishop can reach.        Sample Input 1 4 5      Sample Output 1 10  The bishop can reach the cyan squares in the following figure:        Sample Input 2 7 3      Sample Output 2 11  The bishop can reach the cyan squares in the following figure:        Sample Input 3 1000000000 1000000000      Sample Output 3 500000000000000000

Solution (Python):
import sys
input = sys.stdin.readline
INF = 10 ** 9
MOD = 10 ** 9 + 7

def main():  
    h,w =map(int,input().split())

    ans = 0
    if h == 1 :
        ans = 1
    elif w == 1:
        ans = 1
    else:
        if w%2 == 0:
            ans = h * (w//2)
        else:
            if h % 2 == 0:
                ans = (h//2) * w
            else:
                ans = (h//2) * w + (w//2) + 1

    print(ans)
if __name__=='__main__':
    main()

Solution (Python):
import math

h, w = map(int, input().split(' '))

if h == 1 or w == 1:
    print(1)
else:
    print(math.ceil(h * w / 2))

Solution (Python):
h,w=map(int,input().split())
if h==1 or w==1:
    print(1)
    exit()
if h*w/2!=h*w//2:
    print(h*w//2+1)
    exit()
print(h*w//2)

Solution (Python):
h,w = map(int,input().split())

if(h==1 or w==1):
    print(1)
    exit()

if(h%2==0 or w%2==0):
    print((w*h)//2)
    exit()

print((w*h)//2+1)

Solution (Python):
from math import ceil, floor
H, W = map(int, input().split())
if H == 1 or W == 1:
    print(1)
    exit()
cw = ceil(W / 2)
ch = floor(H / 2)
print(cw * ceil(H / 2) + ch * floor(W / 2))

Solution (Python):
x,y = map(int,input().split())
if x==1 or y == 1:
    print(1)
else:
    Sum = ((x + 1) // 2 )  * (( y + 1) // 2) + (x // 2) * ( y // 2)
    print(Sum)

Solution (Python):
import math
h,w = map(int,input().split())
ans = 0
if h == 1 or w == 1:
    ans = 1
elif (h % 2 == 0 and w % 2 == 1) or (w % 2 == 0 and h % 2 == 1) or (h % 2 == 0 and w % 2 == 0):
    ans += (h/2)*w
else:
    ans += (math.ceil(h/2)*math.ceil(w/2)+math.floor(h/2)*math.floor(w/2))
print(round(ans))

Solution (Python):
def main():
    
    
    H,W = map(int,input().split())
    if W == 1:
        print(1)
        exit()
    elif W%2==0:
        W2 = W/2
        W3 = W/2
    elif W%2==1:
        W2 = W//2+1
        W3 = W//2
    if H == 1:
        print(1)
        exit()
    elif H%2==0:
        H2 = H/2
        H3 = H/2
    elif H%2==1:
        H2 = H//2+1
        H3 = H//2
    mas = W2*H2 + W3*H3

    print(int(mas))

if __name__ == "__main__":
    main()

Solution (Python):
a,b = map(int,input().split())
c = a*b
if a==1 or b==1:
    print(1)
    exit()

if c%2==0:
    print(c//2)
else:
    print(c//2+1)

Solution (Python):
a,b=map(int,input().split())

if a==1 or b==1:
    print(1)
else:
    print((a*b+1)//2)

Solution (Python):
h, w = map(int,input().split())
if h == 1 or w == 1:
    print(1)
else:
    h1 = (h+1) // 2
    h2 = h // 2
    w1 = (w+1) //2
    w2 = w // 2
    print(h1*w1 + h2*w2)

Solution (Python):
H, W = map(int, input().split())

ans = 0

ans += (H + 1) // 2 * ((W + 1) // 2)
ans += H // 2 * (W // 2)

if H == 1 or W == 1:
    ans = 1

print(ans)

Solution (Python):
h, w = map(int, input().split())
if h == 1 or w == 1:
    print(1)
    exit()
ans = 0
ans += ((w // 2) + (w % 2)) * (h // 2 + h % 2) + (w // 2) * (h // 2)

print(ans)

Solution (Python):
h,w=map(int,input().split())
if h==1 or w==1:
  print(1)
  exit()
print((h*w+1)//2)

Solution (Python):
H,W=map(int,input().split())

k=H*W
if H==1 or W==1:
    print(1)
elif k%2 == 0:
    print(int(k/2))
else:
    print(int((k/2)+1))

Solution (Python):
H,W=map(int,input().split())

if H==1 or W==1:
    print(1)
else:
    print(H*W//2 if H*W%2==0 else H*W//2+1)

Solution (Python):
H,W = map(int,input().split())

if W > 1 and H > 1:
    if H*W % 2 == 0:
        print(H*W//2)
    else:
        print(H*W//2+1)
else:
    print(1)

Solution (Python):
import sys
sys.setrecursionlimit(4100000)

import math

import logging

logging.basicConfig(level=logging.DEBUG)

logger = logging.getLogger(__name__)


def resolve():
    
    
    H, W = [int(x) for x in sys.stdin.readline().split()]  
    

    
    
    
    

    logger.debug('{}'.format([]))
    if H == 1 or W == 1:
        print(1)
        return

    a = (H // 2) * (W // 2)
    b = math.ceil(H / 2) * math.ceil(W / 2)
    print(a + b)


if __name__ == "__main__":
    resolve()





import sys
from io import StringIO
import unittest


class TestClass(unittest.TestCase):
    def assertIO(self, input, output):
        stdout, stdin = sys.stdout, sys.stdin
        sys.stdout, sys.stdin = StringIO(), StringIO(input)
        resolve()
        sys.stdout.seek(0)
        out = sys.stdout.read()[:-1]
        sys.stdout, sys.stdin = stdout, stdin
        self.assertEqual(out, output)

    def test_入力例_1(self):
        input = """4 5"""
        output = """10"""
        self.assertIO(input, output)

    def test_入力例_2(self):
        input = """7 3"""
        output = """11"""
        self.assertIO(input, output)

    def test_入力例_3(self):
        input = """1000000000 1000000000"""
        output = """500000000000000000"""
        self.assertIO(input, output)

Solution (Python):
H, W = map(int, input().split())

if (H == 1) or (W == 1):
  print(1)
elif H * W % 2 == 0:
  print(int(H * W / 2))
else:
  print(int(H * W / 2 + 1))

Solution (Python):









h, w = map(int, input().split())

if h == 1 or w == 1:
    print(1)
    exit()

hw  = h*w

if hw%2 == 0:
    print(hw//2)
else:
    print(hw//2 + 1)

Solution (Python):

import sys, math, itertools, collections, bisect
input = lambda: sys.stdin.buffer.readline().rstrip().decode('utf-8')
inf = float('inf') ;mod = 10**9+7
mans = inf ;ans = 0 ;count = 0 ;pro = 1
def ceil(x,y):
  return (x-1)//y+1
h,w = map(int,input().split())
if h == 1 or w == 1:
  print(1);exit()
yoko = ceil(w,2)
yokoteki = w-ceil(w,2)
ans += yoko * ceil(h,2)
ans += yokoteki * (h-ceil(h,2))
print(ans)

Solution (Python):
h,w=map(int,input().split())
if h == 1 or w == 1:
    print(1)
    exit()
if h*w % 2 == 0:
    print(int(h*w/2))
else:
    print(int((h*w//2)+1))

Solution (Python):

import sys
import math

def solve(H: int, W: int):
    if H==1 or W == 1:
        print(1)
    else:
        evenRow = math.ceil(W/2)
        oddRow = math.floor(W/2)
        r = H//2
        extra= evenRow if H %2==1 else 0
        print(r*evenRow+r*oddRow+extra)
    return



def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    H = int(next(tokens))  
    W = int(next(tokens))  
    solve(H, W)

if __name__ == '__main__':
    main()

Solution (Python):
h, w = map(int, input().split())

if(h == 1 or w == 1):
    print(1)
else:
    if(h*w % 2 == 0):
        print(h*w // 2)
    else:
        print(h*w//2 + 1)

Solution (Python):
import math

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

if H == 1 or W == 1:
    print(1)
else:
    h1 = math.ceil(H / 2)
    w1 = math.ceil(W / 2)
    h2 = math.floor(H / 2)
    w2 = math.floor(W / 2)

    print(h1*w1 + h2*w2)

Solution (Python):
h, w = [int(i) for i in input().split()]
if h == 1 or w == 1:
    print(1)
    exit()
    
a = (h + 1) // 2
b = h // 2
c = (w + 1) // 2
d = w // 2
print(a*c+b*d)

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

Solution (Python):
h, w = map(int, input().split())
if h == 1 or w == 1:
  print(1)
elif (h * w) % 2 == 1:
  print((h * w + 1) // 2)
else:
  print((h * w) // 2)

Solution (Python):
H, W = map(int, input().split())
if H == 1 or W == 1:
    print(1)
    exit()

if H*W % 2 != 0:
    print(H*W//2+1)
else:
    print(H*W//2)

Solution (Python):
h, w = map(int, input().split())

num = h * w

if h == 1 or w == 1:
    print(1)
elif num % 2 == 0:
    print(num // 2)
else:
    print(num // 2 + 1)

Solution (Python):
from sys import exit, setrecursionlimit
setrecursionlimit(10**6)

def array2D(row, col ,val=0):
    return [[val]*col for i in range(row)]

from math import ceil
h,w = map(int, input().split())
ans = 0

if h==1 or w == 1:
    print(1)
else:
    print((h-h//2)*(w-w//2) + (h//2) * (w//2))

Solution (Python):
h, w = map(int, input().split())
hw = h * w

if h == 1 or w == 1:
    print(1)
elif hw % 2 == 0:
    print(h * w // 2)
else:
    print(h*w // 2 + 1)

Solution (Python):
n,m = (int(x) for x in input().split())

mul = int(n*m)

if n == 1 or m == 1:
    print(1)
elif mul % 2 == 1:
    print(mul // 2 + 1)
elif mul % 2 == 0:
    print(mul //2)

Solution (Python):
import math
h, w = list(map(int, input().split(" ")))

if h == 1 or w == 1:
    print(1)
    exit()

print(math.ceil((h * w) / 2))

Solution (Python):
N,K=map(int,input().split())

if N==1 or K==1:
  print(1)
else:
  if N%2==0:
    print((N//2)*K)
  else:
    if K%2==0:
      print((K//2)*N)
    else:
      print(N*(K//2)+(N//2)+1)

Solution (Python):
def main():
    h, w = list(map(int, input().split()))
    if (h==1 or w==1):
        print(1)
    elif (h%2==0 or w%2==0):
        print(int((h*w)/2))
    else:
        print(int((h*w)//2+1))

if __name__ == '__main__':
    main()

Solution (Python):
h, w = map(int, input().split())
if h == 1 or w == 1:
    print(1)
else:
    print((h * w + 1) // 2)

Solution (Python):
[H,W]=[int(inp) for inp in input().split()]
if H == 1 or W == 1:
    print(1)
    exit()
yokoKisu = H // 2 + H % 2

sum=H*(W//2)+yokoKisu*(W%2)
print(sum)

Solution (Python):
H,W = map(int, input().split())
if H*W%2 == 0:
    ans = H*W//2
else:
    ans = H*(W-1)//2 + (H+1)//2
if H == 1 or W == 1:
    ans = 1
print(ans)

Solution (Python):
import math
H, W = [int(_) for _ in input().split(" ")]
if (H == 1 or W == 1):
  print(1)
elif (H % 2 == 0):
  print(int(H/2*W))
else:
  print(int(H/2)*W+math.ceil(W/2))

Solution (Python):
h,w=input().strip().split(" ")
h,w=[int(h),int(w)]
p=h*w
if h==1 or w==1:
    print(1)
else:
    if p%2==1:
        print((p//2)+1)
    else:
        print(p//2)

Solution (Python):
H, W = map(int, input().split())

s = H * W

if H == 1 or W == 1:
    print(1)
else:
    if s % 2 == 0:
        print(s // 2)
    else:
        print(s // 2 + 1)

Solution (Python):
H,W = map(int, input().split())

if H == 1 or W == 1:
    ans = 1
else:
    ans = ((H + 2 - 1) // 2) * ((W + 2 - 1) // 2) + (H // 2) * (W//2)
print(ans)

Solution (Python):
h, w = map(int, input().split())
if h == 1 or w == 1:
  print(1)
elif h%2 == 0 and w%2 == 0:
  print(h*w//2)
elif h%2 == 1 and w%2 == 0:
  print((h-1)*w//2 + (w+1)//2)
elif h%2 == 0 and w%2 == 1:
  print(h*(w-1)//2 + (h+1)//2)
elif h%2 == 1 and w%2 == 1:
  print((h-1)*(w-1)//2+(h+1)//2+(w+1)//2-1)

Solution (Python):
H,W=map(int,input().split())
if H==1 or W==1:
  print(1)
  exit(0)
if W%2==0:
  w=W//2
  ans=w*H
else:
  w=W//2 + 1
  ans=w*H
  ans-=H//2
print(ans)

Solution (Python):
import math
def main():
    H,W=map(int, input().split())
    if H == 1 or W == 1:
        print(1)
    else:
        print((H//2)*W + (H%2)*math.ceil(W/2))
    return

if __name__ == '__main__':
    main()

Solution (Python):
h, w = [int(x) for x in input().split()]
if h == 1 or w == 1:
    print(1)
else:
    print((h * w + 1) // 2)

Solution (Python):
H, W = map(int, input().split())
def f(H, W):
    if H == 1 or W == 1:
        return 1
    if H % 2 == 0:
        return H // 2 * W
    else:
        return H // 2 * W + (W+1) // 2
print(f(H, W))

Solution (Python):
H, W = map(int, input().split())

if H == 1 or W == 1:
    print(1)
elif H%2==1 and W%2==1:
    print(int(H * W / 2) + 1)
else:
    print(int(H * W / 2))

Solution (Python):
def main(sample_file = ''):

    """ convenient functions
    
    
    
    
    
    """

    """convenient decorator
    
    
        
        
        
        
        
        
        
        
        
        
    """
    
    
    import sys
    sys.setrecursionlimit(10**7)
    from itertools import accumulate, combinations, permutations, product 
    
    from math import factorial, ceil, floor, sqrt
    def factorize(n):
        """return the factors of the Arg and count of each factor
        
        Args:
            n (long): number to be resolved into factors
        
        Returns:
            list of tuples: factorize(220) returns [(2, 2), (5, 1), (11, 1)]
        """
        fct = []  
        b, e = 2, 0  
        while b * b <= n:
            while n % b == 0:
                n = n // b
                e = e + 1
            if e > 0:
                fct.append((b, e))
            b, e = b + 1, 0
        if n > 1:
            fct.append((n, 1))
        return fct
    def combinations_count(n, r):   
        """Return the number of selecting r pieces of items from n kinds of items.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        
        if n < 0 or r < 0:
            raise Exception('combinations_count(n, r) not defined when n or r is negative')
        if n - r < r: r = n - r
        if r < 0: return 0
        if r == 0: return 1
        if r == 1: return n
        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]
        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot
        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
        return result
    def combinations_with_replacement_count(n, r):
        """Return the number of selecting r pieces of items from n kinds of items allowing individual elements to be repeated more than once.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        if n < 0 or r < 0:
            raise Exception('combinations_with_replacement_count(n, r) not defined when n or r is negative')
        elif n == 0:
            return 1
        else:
            return combinations_count(n + r - 1, r)
    from bisect import bisect_left, bisect_right
    from collections import deque, Counter, defaultdict 
    from heapq import heapify, heappop, heappush, heappushpop, heapreplace,nlargest,nsmallest 
    from copy import deepcopy, copy 
    import operator
    from operator import itemgetter 
    
    
    from functools import reduce, lru_cache
    def chmin(x, y):
        """change minimum
        if x > y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current minimum value
            y (long): potential minimum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x > y:
            x = y
            return (x, True)
        else:
            return (x, False)
    def chmax(x, y):
        """change maximum
        if x < y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current maximum value
            y (long): potential maximum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x < y:
            x = y
            return (x, True)
        else:
            return (x, False)

    from fractions import gcd 
    def gcds(numbers):
        return reduce(gcd, numbers)
    def lcm(x, y):
        return (x * y) // gcd(x, y)
    def lcms(numbers):
        return reduce(lcm, numbers, 1)
    def make_divisors(n, reversed=False):
        """create list of divisors
        
        Args:
            number (int): number from which list of divisors is created
            reversed (bool, optional): ascending order if False. Defaults to False.
        
        Returns:
            list: list of divisors
        """
        divisors = set()
        for i in range(1, int(n**0.5)+1):
            if n % i == 0:
                divisors.add(i)
                divisors.add(n//i)
        return sorted(list(divisors),reverse=reversed)
    
    
    
    INF = 10 ** 18
    MOD = 10 ** 9 + 7
    modpow = lambda a, n, p = MOD: pow(a, n, p) 
    def modinv(a, p = MOD):
        
        
        return modpow(a, p-2, p)
    def modinv_list(n, p = MOD):
        if n <= 1:
            return [0,1][:n+1]
        else:
            inv_t = [0,1]
            for i in range(2, n+1):
                inv_t += [inv_t[p % i] * (p - int(p / i)) % p]
            return inv_t
    def modfactorial_list(n, p = MOD):
        if n == 0:
            return [1]
        else:
            l = [0] * (n+1)
            tmp = 1
            for i in range(1, n+1):
                tmp = tmp * i % p
                l[i] = tmp
            return l
    def modcomb(n, k, fac_list = [], p = MOD):
        
        
        from math import factorial
        if n < 0 or k < 0 or n < k: return 0
        if n == 0 or k == 0: return 1
        if len(fac_list) <= n:
            a = factorial(n) % p
            b = factorial(k) % p
            c = factorial(n-k) % p
        else:
            a = fac_list[n]
            b = fac_list[k]
            c = fac_list[n-k]
        return (a * modpow(b, p-2, p) * modpow(c, p-2, p)) % p
    def modadd(a, b, p = MOD):
        return (a + b) % MOD
    def modsub(a, b, p = MOD):
        return (a - b) % p
    def modmul(a, b, p = MOD):
        return ((a % p) * (b % p)) % p
    def moddiv(a, b, p = MOD):
        return modmul(a, modpow(b, p-2, p))

    class UnionFindTree:
        """union find tree class
        TODO: fix this description...
        how to use (example):
        >>  uf = UnionFindTree(N) 
        >>  if uf.find_root(a) == uf.find_root(b):
        >>      do something
        >>  else:
        >>      do something
        >>      uf.unite(a, b)
        """
        def __init__(self, N):
            self.root = [-1] * (N+1)
            self.rank   = [0]  * (N+1)
            self.connected_num = [1] * (N+1)
    
        def find_root(self,x):
            root = self.root
            while root[x] != -1:
                x = root[x]
            return x
    
        def unite(self,x,y):
            root = self.root
            rank = self.rank
            connected_num = self.connected_num
            find_root = self.find_root
    
            rx = find_root(x)
            ry = find_root(y)
            if rx != ry:
                if rank[rx] < rank[ry]:
                    root[rx] = ry
                    rx,ry = ry,rx
                else:
                    if rank[rx] == rank[ry]:
                        rank[rx] += 1
                    root[ry] = rx       
                connected_num[rx] += connected_num[ry]

    
    
    
    
    

    def BellmanFord(N, M, ABC, vertex_start, vertex_end, value_if_inf = -1, find_shortest = False):
        """to calculate furthest or shortest length between vertex_start and vertex_end using BellmanFord algorithm
        
        Args:
            N (int): number of vertices
            M (int): number of edges
            ABC (list): [(ai, bi, ci) for _ in range(N)] where i-th edge is directed from vertex ai to vertex bi and the length is ci 
            vertex_start (int): start vertex. usually use 0.
            vertex_end (int): end vertex. usually use N-1.
            value_if_inf (int or string as you like, optional): value you want when the furthest (or shortest) distance is infinite (or -infinite). Defaults to -1.
            find_shortest (bool, optional): choose False to find furthest path. Defaults to False.
        
        Returns:
            int or string: normally int (but can be str if you set value_if_inf to str)
            
        Example:
                N, M, P = R()
                ABC = [R() for _ in range(M)]
                ABC = [(a-1, b-1, c-P) for a, b, c in ABC]
                print(BellmanFord(N, M, ABC, 0, N-1, value_if_inf = 'inf'))

        """

        def make_reachable_list(N, M, ABC, vertex_start, vertex_end):
            reachable_to_direct = defaultdict(list)
            reachable_from_direct = defaultdict(list)
            reachable_from_start = [False] * N
            reachable_to_end = [False] * N
            reachable_from_start[vertex_start] = True
            reachable_to_end[vertex_end] = True
            reachable_from_both_sides = [False] * N
            dfs_from_start = []
            dfs_to_end = []
            for a, b, c in ABC:
                reachable_to_direct[a].append(b)
                reachable_from_direct[b].append(a)
                if a == vertex_start:
                    dfs_from_start.append(b)
                    reachable_from_start[b] = True
                if b == vertex_end:
                    dfs_to_end.append(a)
                    reachable_to_end[a] = True
            while dfs_from_start:
                v = dfs_from_start.pop()
                for i in reachable_to_direct[v]:
                    if not reachable_from_start[i]:
                        reachable_from_start[i] = True
                        dfs_from_start.append(i)
            while dfs_to_end:
                v = dfs_to_end.pop()
                for i in reachable_from_direct[v]:
                    if not reachable_to_end[i]:
                        reachable_to_end[i] = True
                        dfs_to_end.append(i)
            for i in range(N):
                reachable_from_both_sides[i] = reachable_from_start[i] and reachable_to_end[i]
            return reachable_from_both_sides
        
        reachable_from_both_sides = make_reachable_list(N, M, ABC, vertex_start, vertex_end)
        
        if find_shortest:
            dist = [INF for i in range(N)]
        else:
            dist = [-INF for i in range(N)]
        
        dist[vertex_start] = 0
        for i in range(N):
            updated = False
            for a, b, c in ABC:
                if not reachable_from_both_sides[a]:
                    continue
                elif find_shortest:
                    update_condition = dist[a] + c < dist[b]
                else:
                    update_condition = dist[a] + c > dist[b]
                if dist[a] != INF and update_condition:
                    dist[b] = dist[a] + c
                    updated = True
                    if i == N-1:
                        return value_if_inf
            if not updated:
                break
        return dist[vertex_end]

    """ initialize variables and set inputs
    
        
        
            
            
    
        
        
        
        
        
        
        
    
        
        
        
        
    
        
        
    """

    
    r = lambda: sys.stdin.readline().strip()
    r_int = lambda: int(r())
    r_float = lambda: float(r())
    R = lambda: list(map(int, r().split()))
    R_str = lambda: r().split()
    R_map = lambda: map(int, r().split())
    R_float = lambda: list(map(float, r().split()))
    R_tuple = lambda: tuple(map(int, r().split()))

    """ how to treat input
    
    
    
    
    
    
    
    """

    
    if sample_file:
        sys.stdin = open(sample_file)
        
    
    
    
    H, W = R()
    if H==1 or W == 1:
        print(1)
    elif H % 2 == 0 and W % 2 == 0:
        print(H*W//2)
    elif H % 2 != 0 and W % 2 != 0:
        print(H*W//2+1)
    else:
        print(H*W//2)
    
    
    

    """memo: how to use defaultdict of list
    
    Dic = defaultdict(list)
    
    Dic[x].append(y)
    
    for k, v in Dic.items():
    """
    
    """memo: how to solve binary problems
    
    >>> a = 5
    >>> bin_str_a = format(a, '
    >>> print(bin_str_a)
    0b0101 
    """
    
    """memo: how to solve the problem
    creating simple test/answer
    greed
    simple dp
    graph
    """

if __name__ == '__main__':
    main()

Solution (Python):
def main():
    H, W = map(int, input().split())
    if H == 1 or W == 1:
        print(1)
    else:
        print(-(-H*W//2))


if __name__ == "__main__":
    main()

Solution (Python):
n,m=map(int,input().split())
if n==1 or m==1:
  print(1)
  exit()
print(m//2*n+m%2*(n//2+n%2))

Solution (Python):
import sys
input = lambda: sys.stdin.readline().rstrip() 

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

if __name__ == '__main__':
    resolve()

Solution (Python):
import sys
input = sys.stdin.readline

H, W = map(int, input().split())
if H == 1 or W == 1:
    ans = 1
elif H%2 == 1 and W%2 == 1:
    ans = H*(W//2) + (H+1)//2
else:
    ans = H*W//2
print(ans)

Solution (Python):
import math
list = input().split(" ")
H = int(list[0])
W = int(list[1])

if (W == 1) or (H == 1):
    print(1)
else:
    print(math.ceil(H*W/2))

Solution (Python):
h, w = map(int, input().split())
if h == 1 or w == 1:
    print(1)
else:
    print(-(-(h * w) // 2))

Solution (Python):
a, b = map(int, input().split())
if a == 1:
  out = 1
elif b == 1:
  out = 1
elif a+b % 2 == 0:
  out = int(a*b/2)
else:
  out = int((a*b+1)/2)
print (out)

Solution (Python):

h, w = map(int, input().split())
if h == 1 or w == 1:
    print(1)
    exit()
print(((h + 1) // 2) * ((w + 1) // 2) + (h // 2) * (w // 2))

Solution (Python):
H,W = map(int, input().split())
if H==1 or W==1:
  print(1)
else:
  print(-(-(H*W)//2))

Solution (Python):
h,w=map(int,input().split())
if h==1 or w==1:
 print(1)
else:
 print(((h+1)//2)*((w+1)//2)+(h//2)*(w//2))

Solution (Python):
H,W=list(map(int,input().split()))
HW=H*W
if H==1 or W==1:
    print(1)
else:
    if HW%2==0:
        print(int(HW/2))
    else:
        print(int(HW/2)+1)

Solution (Python):


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

if H == 1 or W == 1 :
  print(1)
  exit()

print(-(-(H * W) // 2))

Solution (Python):
import math
H, W = map(int, input().split())
if H == 1 or W == 1:
    print(1)
elif H % 2 == 1 and W % 2 == 1:
    print(math.ceil(H*W/2))
else:
    print(int(H*W/2))

Solution (Python):
h, w = map(int, input().split())

a = h * w

if h == 1 or w == 1:
    print(1)
    exit()

if a % 2 == 0:
    print(a//2)
else:
    print(a//2 + 1)

Solution (Python):
from math import ceil


def main():
    h, w = map(int, input().split())
    print(w * (h // 2) + ceil(w / 2) * (h % 2) if h > 1 and w > 1 else 1)


if __name__ == '__main__':
    main()

Solution (Python):
import math
a, b = list(map(int, input().split()))

if a == 2 and b == 2:
    print(1)
    exit() 
if a == 1 or b == 1:
    print(1)
    exit() 
r = math.ceil(a*b/2)
print(r)

Solution (Python):


h, w = (int(val) for val in input().split())
t = int((h * w + 1) / 2)
if h == 1 or w == 1:
    t = 1
print(t)

Solution (Python):
h,w = map(int,input().split())
c = h*w
if h==1 or w==1:
    ans = 1
elif c%2==0:
    ans = c/2
else:
    ans = c/2+1
print(int(ans))

Solution (Python):
a, b = map(int, input().split())

n = a*b

if a == 1 or b == 1:
    print(1)
elif n % 2 == 1:
    print(n//2 + 1)
else:
    print(n//2)

Solution (Python):
import queue
import math
import copy
"""
N = int(input())



A = []
for i in range(N):
	A.append(int(input()))

print(A)

"""
(N,M) = (int(i) for i in input().split(" "))
if N==1 or M==1:
	print(1)
else:
	S = N%2 + M%2
	T = (N-N%2)*(M-M%2)//2
	if N%2:
		T += (M+1)//2
	if M%2:
		T += (N+1)//2
	if S == 2:
		T -= 1
	print(T)

Solution (Python):
H,W = [int(i) for i in input().split()]

if (H ==1) | (W ==1):
 	ans = 1
  
elif (H%2 ==1) & (W%2==1):
    ans = int(H*W//2 +1)
else:
    ans = int(H*W/2)
    
print(ans)

Solution (Python):
a,b = map(int,input().split())
menseki = a*b
if a == 1 or b == 1:
    ans = 1
else:
    ans = menseki // 2 + menseki % 2
print(ans)

Solution (Python):
class Solution:
    def solve(self, H: int, W: int) -> int:

        if H == 1 or W == 1:
            return 1
        else:
            return (H*W + 1) // 2


if __name__ == '__main__':

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

    
    solution = Solution()
    print(solution.solve(H, W))

Solution (Python):
a=input().split(" ")
b=int(a[0])*int(a[1])
if int(a[0])==1 or int(a[1])==1:
    print(1)
else:
    if b%2==0:
        print(b//2)
    else:
        print(b//2+1)

Solution (Python):
import itertools
from collections import deque,defaultdict,Counter
from itertools import accumulate
import bisect
from heapq import heappop,heappush,heapify
from fractions import gcd
from copy import deepcopy
import math
import queue


Mod = 1000000007
import sys
sys.setrecursionlimit(100000) 
  
def sieve_of_eratosthenes(n):
    if not isinstance(n,int):
        raise TypeError("n is not int")
    if n<2:
        raise ValueError("n is not effective")
    prime = [1]*(n+1)
    for i in range(2,int(math.sqrt(n))+1):
        if prime[i] == 1:
            for j in range(2*i,n+1):
                if j%i == 0:
                    prime[j] = 0
    res = []
    for i in range(2,n+1):
        if prime[i] == 1:
            res.append(i)
    return res

 
class UnionFind:
    def __init__(self,n):
        self.parent = [i for i in range(n+1)]
        self.rank = [0 for i in range(n+1)]
    
    def findroot(self,x):
        if x == self.parent[x]:
            return x
        else:
            y = self.parent[x]
            y = self.findroot(self.parent[x])
            return y
    
    def union(self,x,y):
        px = self.findroot(x)
        py = self.findroot(y)
        if px < py:
            self.parent[py] = px
        else:
            self.parent[px] = py
 
    def same_group_or_no(self,x,y):
        return self.findroot(x) == self.findroot(y)

def main(): 
    h,w = map(int,input().split())
    if not (h == 1 or w == 1): 
        print(h*w // 2 if h % 2 == 0 or w % 2 == 0 else h*w // 2 + 1)
    else:
        print(1)
if __name__ == "__main__":
    main()

Solution (Python):
H, W = map(int, input().split())

if H == 1 or W == 1:
    print(1)
    exit()
    
print(-(-H // 2) * -(-W // 2) + (H // 2) * (W // 2))