#include <stdio.h>
int main(void){
  long H,W;
  scanf("%ld %ld",&H,&W);
  
if(H == 1 || W == 1)
{
printf("1");
  return 0;
}
if (H * W %2 == 0)
{
printf("%ld",H * W / 2);
  return 0;
}
 else
{
printf("%ld",H * W / 2 + 1);
  return 0;
}
 
}
; ModuleID = '/data/TheStack_IR/OJ_Samples/Collated/ObjectiveC/Source_168/source.m'
source_filename = "/data/TheStack_IR/OJ_Samples/Collated/ObjectiveC/Source_168/source.m"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

@.str = private unnamed_addr constant [8 x i8] c"%ld %ld\00", align 1
@.str.2 = private unnamed_addr constant [4 x i8] c"%ld\00", align 1

; Function Attrs: nofree nounwind uwtable
define dso_local i32 @main() local_unnamed_addr #0 {
entry:
  %H = alloca i64, align 8
  %W = alloca i64, align 8
  call void @llvm.lifetime.start.p0(i64 8, ptr nonnull %H) #4
  call void @llvm.lifetime.start.p0(i64 8, ptr nonnull %W) #4
  %call = call i32 (ptr, ...) @__isoc99_scanf(ptr noundef nonnull @.str, ptr noundef nonnull %H, ptr noundef nonnull %W)
  %0 = load i64, ptr %H, align 8, !tbaa !5
  %cmp = icmp eq i64 %0, 1
  %1 = load i64, ptr %W, align 8
  %cmp1 = icmp eq i64 %1, 1
  %or.cond = select i1 %cmp, i1 true, i1 %cmp1
  br i1 %or.cond, label %if.then, label %if.end

if.then:                                          ; preds = %entry
  %putchar = call i32 @putchar(i32 49)
  br label %cleanup

if.end:                                           ; preds = %entry
  %mul = mul nsw i64 %1, %0
  %2 = and i64 %mul, 1
  %cmp3 = icmp eq i64 %2, 0
  %div = sdiv i64 %mul, 2
  br i1 %cmp3, label %if.then4, label %if.else

if.then4:                                         ; preds = %if.end
  %call6 = call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str.2, i64 noundef %div)
  br label %cleanup

if.else:                                          ; preds = %if.end
  %add = add nsw i64 %div, 1
  %call9 = call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str.2, i64 noundef %add)
  br label %cleanup

cleanup:                                          ; preds = %if.else, %if.then4, %if.then
  call void @llvm.lifetime.end.p0(i64 8, ptr nonnull %W) #4
  call void @llvm.lifetime.end.p0(i64 8, ptr nonnull %H) #4
  ret i32 0
}

; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: nofree nounwind
declare noundef i32 @__isoc99_scanf(ptr nocapture noundef readonly, ...) local_unnamed_addr #2

; Function Attrs: nofree nounwind
declare noundef i32 @printf(ptr nocapture noundef readonly, ...) local_unnamed_addr #2

; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: nofree nounwind
declare noundef i32 @putchar(i32 noundef) local_unnamed_addr #3

attributes #0 = { nofree nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #1 = { mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #2 = { nofree nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #3 = { nofree nounwind }
attributes #4 = { nounwind }

!llvm.linker.options = !{}
!llvm.module.flags = !{!0, !1, !2, !3}
!llvm.ident = !{!4}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 8, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 2}
!4 = !{!"Ubuntu clang version 18.0.0 (++20231007042255+8abb2ace888b-1~exp1~20231007042414.1230)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"long", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
