#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
    int n,k,x,y;
    while(~scanf("%d %d %d %d",&n,&k,&x,&y))
    {

        if(n>k)
            printf("%d\n", x*k+(n-k)*y);
        else

            printf("%d\n", x*n);

    }

    return 0;
}

; ModuleID = '/data/TheStack_IR/OJ_Samples/Collated/ObjectiveC/Source_911/source.m'
source_filename = "/data/TheStack_IR/OJ_Samples/Collated/ObjectiveC/Source_911/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 [12 x i8] c"%d %d %d %d\00", align 1
@.str.1 = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1

; Function Attrs: minsize nofree nounwind optsize uwtable
define dso_local i32 @main() local_unnamed_addr #0 {
entry:
  %n = alloca i32, align 4
  %k = alloca i32, align 4
  %x = alloca i32, align 4
  %y = alloca i32, align 4
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %n) #3
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %k) #3
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %x) #3
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %y) #3
  br label %while.cond

while.cond:                                       ; preds = %if.end, %entry
  %call = call i32 (ptr, ...) @__isoc99_scanf(ptr noundef nonnull @.str, ptr noundef nonnull %n, ptr noundef nonnull %k, ptr noundef nonnull %x, ptr noundef nonnull %y) #4
  %tobool.not = icmp eq i32 %call, -1
  br i1 %tobool.not, label %while.end, label %while.body

while.body:                                       ; preds = %while.cond
  %0 = load i32, ptr %n, align 4, !tbaa !5
  %1 = load i32, ptr %k, align 4, !tbaa !5
  %cmp = icmp sgt i32 %0, %1
  %2 = load i32, ptr %x, align 4, !tbaa !5
  br i1 %cmp, label %if.then, label %if.else

if.then:                                          ; preds = %while.body
  %mul = mul nsw i32 %2, %1
  %sub = sub nsw i32 %0, %1
  %3 = load i32, ptr %y, align 4, !tbaa !5
  %mul1 = mul nsw i32 %3, %sub
  %add = add nsw i32 %mul1, %mul
  br label %if.end

if.else:                                          ; preds = %while.body
  %mul3 = mul nsw i32 %2, %0
  br label %if.end

if.end:                                           ; preds = %if.else, %if.then
  %mul3.sink = phi i32 [ %mul3, %if.else ], [ %add, %if.then ]
  %call4 = call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str.1, i32 noundef %mul3.sink) #4
  br label %while.cond

while.end:                                        ; preds = %while.cond
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %y) #3
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %x) #3
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %k) #3
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %n) #3
  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: minsize nofree nounwind optsize
declare noundef i32 @__isoc99_scanf(ptr nocapture noundef readonly, ...) local_unnamed_addr #2

; Function Attrs: minsize nofree nounwind optsize
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

attributes #0 = { minsize nofree nounwind optsize 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 = { minsize nofree nounwind optsize "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 = { nounwind }
attributes #4 = { minsize optsize }

!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 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
