; LLVM IR from Leet-Us-Code/DSA-A-Z-Practice :: Sid's Levels/Level - 2/Backtracking (MColourProblem)

; Unoptimized IR (clang -disable-llvm-passes):
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

%"class.std::basic_istream" = type { ptr, i64, %"class.std::basic_ios" }
%"class.std::basic_ios" = type { %"class.std::ios_base", ptr, i8, i8, ptr, ptr, ptr, ptr }
%"class.std::ios_base" = type { ptr, i64, i64, i32, i32, i32, ptr, %"struct.std::ios_base::_Words", [8 x %"struct.std::ios_base::_Words"], i32, ptr, %"class.std::locale" }
%"struct.std::ios_base::_Words" = type { ptr, i64 }
%"class.std::locale" = type { ptr }
%"class.std::basic_ostream" = type { ptr, %"class.std::basic_ios" }

@_ZSt3cin = external global %"class.std::basic_istream", align 8
@_ZSt4cout = external global %"class.std::basic_ostream", align 8

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: mustprogress uwtable
declare dso_local noundef zeroext i1 @_Z13graphColoringPA101_bii(ptr noundef, i32 noundef, i32 noundef) #1

; Function Attrs: mustprogress norecurse uwtable
define dso_local noundef i32 @main() #2 {
  %1 = alloca i32, align 4
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  %7 = alloca [101 x [101 x i8]], align 16
  %8 = alloca i32, align 4
  %9 = alloca i32, align 4
  store i32 0, ptr %1, align 4
  call void @llvm.lifetime.start.p0(i64 4, ptr %2) #6
  %10 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) %2)
  br label %11

11:                                               ; preds = %58, %0
  %12 = load i32, ptr %2, align 4, !tbaa !5
  %13 = add nsw i32 %12, -1
  store i32 %13, ptr %2, align 4, !tbaa !5
  %14 = icmp ne i32 %12, 0
  br i1 %14, label %15, label %65

15:                                               ; preds = %11
  call void @llvm.lifetime.start.p0(i64 4, ptr %3) #6
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #6
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #6
  %16 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) %3)
  %17 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) %16, ptr noundef nonnull align 4 dereferenceable(4) %4)
  %18 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) %17, ptr noundef nonnull align 4 dereferenceable(4) %5)
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #6
  call void @llvm.lifetime.start.p0(i64 10201, ptr %7) #6
  store i32 0, ptr %6, align 4, !tbaa !5
  br label %19

19:                                               ; preds = %28, %15
  %20 = load i32, ptr %6, align 4, !tbaa !5
  %21 = load i32, ptr %3, align 4, !tbaa !5
  %22 = icmp slt i32 %20, %21
  br i1 %22, label %23, label %31

23:                                               ; preds = %19
  %24 = load i32, ptr %6, align 4, !tbaa !5
  %25 = sext i32 %24 to i64
  %26 = getelementptr inbounds [101 x [101 x i8]], ptr %7, i64 0, i64 %25
  %27 = getelementptr inbounds [101 x i8], ptr %26, i64 0, i64 0
  call void @llvm.memset.p0.i64(ptr align 1 %27, i8 0, i64 101, i1 false)
  br label %28

28:                                               ; preds = %23
  %29 = load i32, ptr %6, align 4, !tbaa !5
  %30 = add nsw i32 %29, 1
  store i32 %30, ptr %6, align 4, !tbaa !5
  br label %19, !llvm.loop !9

31:                                               ; preds = %19
  store i32 0, ptr %6, align 4, !tbaa !5
  br label %32

32:                                               ; preds = %55, %31
  %33 = load i32, ptr %6, align 4, !tbaa !5
  %34 = load i32, ptr %5, align 4, !tbaa !5
  %35 = icmp slt i32 %33, %34
  br i1 %35, label %36, label %58

36:                                               ; preds = %32
  call void @llvm.lifetime.start.p0(i64 4, ptr %8) #6
  call void @llvm.lifetime.start.p0(i64 4, ptr %9) #6
  %37 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) %8)
  %38 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) %37, ptr noundef nonnull align 4 dereferenceable(4) %9)
  %39 = load i32, ptr %8, align 4, !tbaa !5
  %40 = sub nsw i32 %39, 1
  %41 = sext i32 %40 to i64
  %42 = getelementptr inbounds [101 x [101 x i8]], ptr %7, i64 0, i64 %41
  %43 = load i32, ptr %9, align 4, !tbaa !5
  %44 = sub nsw i32 %43, 1
  %45 = sext i32 %44 to i64
  %46 = getelementptr inbounds [101 x i8], ptr %42, i64 0, i64 %45
  store i8 1, ptr %46, align 1, !tbaa !11
  %47 = load i32, ptr %9, align 4, !tbaa !5
  %48 = sub nsw i32 %47, 1
  %49 = sext i32 %48 to i64
  %50 = getelementptr inbounds [101 x [101 x i8]], ptr %7, i64 0, i64 %49
  %51 = load i32, ptr %8, align 4, !tbaa !5
  %52 = sub nsw i32 %51, 1
  %53 = sext i32 %52 to i64
  %54 = getelementptr inbounds [101 x i8], ptr %50, i64 0, i64 %53
  store i8 1, ptr %54, align 1, !tbaa !11
  call void @llvm.lifetime.end.p0(i64 4, ptr %9) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr %8) #6
  br label %55

55:                                               ; preds = %36
  %56 = load i32, ptr %6, align 4, !tbaa !5
  %57 = add nsw i32 %56, 1
  store i32 %57, ptr %6, align 4, !tbaa !5
  br label %32, !llvm.loop !13

58:                                               ; preds = %32
  %59 = getelementptr inbounds [101 x [101 x i8]], ptr %7, i64 0, i64 0
  %60 = load i32, ptr %4, align 4, !tbaa !5
  %61 = load i32, ptr %3, align 4, !tbaa !5
  %62 = call noundef zeroext i1 @_Z13graphColoringPA101_bii(ptr noundef %59, i32 noundef %60, i32 noundef %61)
  %63 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEb(ptr noundef nonnull align 8 dereferenceable(8) @_ZSt4cout, i1 noundef zeroext %62)
  %64 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEPFRSoS_E(ptr noundef nonnull align 8 dereferenceable(8) %63, ptr noundef @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_)
  call void @llvm.lifetime.end.p0(i64 10201, ptr %7) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr %3) #6
  br label %11, !llvm.loop !14

65:                                               ; preds = %11
  call void @llvm.lifetime.end.p0(i64 4, ptr %2) #6
  ret i32 0
}

declare noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16), ptr noundef nonnull align 4 dereferenceable(4)) #3

; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: write)
declare void @llvm.memset.p0.i64(ptr nocapture writeonly, i8, i64, i1 immarg) #4

; Function Attrs: mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEb(ptr noundef nonnull align 8 dereferenceable(8), i1 noundef zeroext) #1 align 2

; Function Attrs: mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEPFRSoS_E(ptr noundef nonnull align 8 dereferenceable(8), ptr noundef) #1 align 2

; Function Attrs: inlinehint mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_(ptr noundef nonnull align 8 dereferenceable(8)) #5

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { mustprogress 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 #2 = { mustprogress norecurse 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 #3 = { "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 #4 = { nocallback nofree nounwind willreturn memory(argmem: write) }
attributes #5 = { inlinehint mustprogress 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 #6 = { nounwind }

!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 = !{!"clang version 19.1.0 (git@github.com:llvm/llvm-project.git a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}
!11 = !{!12, !12, i64 0}
!12 = !{!"bool", !7, i64 0}
!13 = distinct !{!13, !10}
!14 = distinct !{!14, !10}


; Optimized IR (opt -passes='default<O3>'):
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

%"class.std::basic_istream" = type { ptr, i64, %"class.std::basic_ios" }
%"class.std::basic_ios" = type { %"class.std::ios_base", ptr, i8, i8, ptr, ptr, ptr, ptr }
%"class.std::ios_base" = type { ptr, i64, i64, i32, i32, i32, ptr, %"struct.std::ios_base::_Words", [8 x %"struct.std::ios_base::_Words"], i32, ptr, %"class.std::locale" }
%"struct.std::ios_base::_Words" = type { ptr, i64 }
%"class.std::locale" = type { ptr }
%"class.std::basic_ostream" = type { ptr, %"class.std::basic_ios" }

@_ZSt3cin = external global %"class.std::basic_istream", align 8
@_ZSt4cout = external global %"class.std::basic_ostream", align 8

; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: mustprogress uwtable
declare dso_local noundef zeroext i1 @_Z13graphColoringPA101_bii(ptr noundef, i32 noundef, i32 noundef) local_unnamed_addr #1

; Function Attrs: mustprogress norecurse uwtable
define dso_local noundef i32 @main() local_unnamed_addr #2 {
  %1 = alloca i32, align 4
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca [101 x [101 x i8]], align 16
  %6 = alloca i32, align 4
  %7 = alloca i32, align 4
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %1) #6
  %8 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) %1)
  %9 = load i32, ptr %1, align 4, !tbaa !5
  %10 = add nsw i32 %9, -1
  store i32 %10, ptr %1, align 4, !tbaa !5
  %.not8 = icmp eq i32 %9, 0
  br i1 %.not8, label %._crit_edge11, label %.lr.ph10

.lr.ph10:                                         ; preds = %0, %._crit_edge
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %2) #6
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %3) #6
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %4) #6
  %11 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) %2)
  %12 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) %11, ptr noundef nonnull align 4 dereferenceable(4) %3)
  %13 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) %12, ptr noundef nonnull align 4 dereferenceable(4) %4)
  call void @llvm.lifetime.start.p0(i64 10201, ptr nonnull %5) #6
  %14 = load i32, ptr %2, align 4, !tbaa !5
  %15 = icmp sgt i32 %14, 0
  br i1 %15, label %.lr.ph.preheader, label %.preheader

.lr.ph.preheader:                                 ; preds = %.lr.ph10
  %16 = zext nneg i32 %14 to i64
  %17 = mul nuw nsw i64 %16, 101
  call void @llvm.memset.p0.i64(ptr nonnull align 16 %5, i8 0, i64 %17, i1 false)
  br label %.preheader

.preheader:                                       ; preds = %.lr.ph.preheader, %.lr.ph10
  %18 = load i32, ptr %4, align 4, !tbaa !5
  %19 = icmp sgt i32 %18, 0
  br i1 %19, label %.lr.ph7, label %._crit_edge

.lr.ph7:                                          ; preds = %.preheader, %.lr.ph7
  %.16 = phi i32 [ %30, %.lr.ph7 ], [ 0, %.preheader ]
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %6) #6
  call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %7) #6
  %20 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) %6)
  %21 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) %20, ptr noundef nonnull align 4 dereferenceable(4) %7)
  %22 = load i32, ptr %6, align 4, !tbaa !5
  %23 = add nsw i32 %22, -1
  %24 = sext i32 %23 to i64
  %25 = load i32, ptr %7, align 4, !tbaa !5
  %26 = add nsw i32 %25, -1
  %27 = sext i32 %26 to i64
  %28 = getelementptr inbounds [101 x [101 x i8]], ptr %5, i64 0, i64 %24, i64 %27
  store i8 1, ptr %28, align 1, !tbaa !9
  %29 = getelementptr inbounds [101 x [101 x i8]], ptr %5, i64 0, i64 %27, i64 %24
  store i8 1, ptr %29, align 1, !tbaa !9
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %7) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %6) #6
  %30 = add nuw nsw i32 %.16, 1
  %31 = load i32, ptr %4, align 4, !tbaa !5
  %32 = icmp slt i32 %30, %31
  br i1 %32, label %.lr.ph7, label %._crit_edge.loopexit, !llvm.loop !11

._crit_edge.loopexit:                             ; preds = %.lr.ph7
  %.pre = load i32, ptr %2, align 4, !tbaa !5
  br label %._crit_edge

._crit_edge:                                      ; preds = %._crit_edge.loopexit, %.preheader
  %33 = phi i32 [ %.pre, %._crit_edge.loopexit ], [ %14, %.preheader ]
  %34 = load i32, ptr %3, align 4, !tbaa !5
  %35 = call noundef zeroext i1 @_Z13graphColoringPA101_bii(ptr noundef nonnull %5, i32 noundef %34, i32 noundef %33)
  %36 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEb(ptr noundef nonnull align 8 dereferenceable(8) @_ZSt4cout, i1 noundef zeroext %35)
  %37 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEPFRSoS_E(ptr noundef nonnull align 8 dereferenceable(8) %36, ptr noundef nonnull @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_)
  call void @llvm.lifetime.end.p0(i64 10201, ptr nonnull %5) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %4) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %3) #6
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %2) #6
  %38 = load i32, ptr %1, align 4, !tbaa !5
  %39 = add nsw i32 %38, -1
  store i32 %39, ptr %1, align 4, !tbaa !5
  %.not = icmp eq i32 %38, 0
  br i1 %.not, label %._crit_edge11, label %.lr.ph10, !llvm.loop !13

._crit_edge11:                                    ; preds = %._crit_edge, %0
  call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %1) #6
  ret i32 0
}

declare noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16), ptr noundef nonnull align 4 dereferenceable(4)) local_unnamed_addr #3

; Function Attrs: mustprogress nocallback nofree nounwind willreturn memory(argmem: write)
declare void @llvm.memset.p0.i64(ptr nocapture writeonly, i8, i64, i1 immarg) #4

; Function Attrs: mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEb(ptr noundef nonnull align 8 dereferenceable(8), i1 noundef zeroext) local_unnamed_addr #1 align 2

; Function Attrs: mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEPFRSoS_E(ptr noundef nonnull align 8 dereferenceable(8), ptr noundef) local_unnamed_addr #1 align 2

; Function Attrs: inlinehint mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_(ptr noundef nonnull align 8 dereferenceable(8)) #5

attributes #0 = { mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { mustprogress 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 #2 = { mustprogress norecurse 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 #3 = { "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 #4 = { mustprogress nocallback nofree nounwind willreturn memory(argmem: write) }
attributes #5 = { inlinehint mustprogress 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 #6 = { nounwind }

!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 = !{!"clang version 19.1.0 (git@github.com:llvm/llvm-project.git a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"bool", !7, i64 0}
!11 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}
!13 = distinct !{!13, !12}


; Effective O3 passes: EarlyCSEPass,GVNPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,JumpThreadingPass,LICMPass,LoopIdiomRecognizePass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,SROAPass,SimplifyCFGPass