#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */

/* Variables and functions */
int /*<<< orphan*/ fgets(char *, int, int /*<<< orphan*/);
int /*<<< orphan*/ printf(char *, char *);
int /*<<< orphan*/ stdin;
int strlen(char *);
int main() {
  char a[5000], b;
  fgets(a, sizeof a, stdin);
  int i, k;
  k = strlen(a) - 1;
  for (i = 0; i < k; i++, k--) {
    b = a[i];
    a[i] = a[k];
    a[k] = b;
  }
  printf("%s", a);
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x13a0,%rsp
movl   $0x0,-0x4(%rbp)
lea    -0x1390(%rbp),%rdi
mov    0x2e98(%rip),%rax
mov    (%rax),%edx
mov    $0x1388,%esi
call   1050 <fgets@plt>
lea    -0x1390(%rbp),%rdi
call   1030 <strlen@plt>
sub    $0x1,%eax
mov    %eax,-0x139c(%rbp)
movl   $0x0,-0x1398(%rbp)
mov    -0x1398(%rbp),%eax
cmp    -0x139c(%rbp),%eax
jge    11f4 <main+0xc4>
movslq -0x1398(%rbp),%rax
mov    -0x1390(%rbp,%rax,1),%al
mov    %al,-0x1391(%rbp)
movslq -0x139c(%rbp),%rax
mov    -0x1390(%rbp,%rax,1),%cl
movslq -0x1398(%rbp),%rax
mov    %cl,-0x1390(%rbp,%rax,1)
mov    -0x1391(%rbp),%cl
movslq -0x139c(%rbp),%rax
mov    %cl,-0x1390(%rbp,%rax,1)
mov    -0x1398(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x1398(%rbp)
mov    -0x139c(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0x139c(%rbp)
jmp    117b <main+0x4b>
lea    -0x1390(%rbp),%rsi
lea    0xdfe(%rip),%rdi
call   1040 <printf@plt>
xor    %eax,%eax
add    $0x13a0,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbx
sub    $0x1390,%rsp
mov    0x2ea9(%rip),%rax
mov    (%rax),%edx
mov    %rsp,%rbx
mov    %rbx,%rdi
mov    $0x1388,%esi
call   1050 <fgets@plt>
mov    %rbx,%rdi
call   1030 <strlen@plt>
cmp    $0x2,%eax
jl     1190 <main+0x60>
mov    %eax,%eax
add    $0xfffffffffffffffe,%rax
xor    %ecx,%ecx
cs nopw 0x0(%rax,%rax,1)
movzbl (%rsp,%rcx,1),%edx
movzbl 0x1(%rsp,%rax,1),%ebx
mov    %bl,(%rsp,%rcx,1)
mov    %dl,0x1(%rsp,%rax,1)
add    $0x1,%rcx
lea    -0x1(%rax),%rdx
cmp    %rax,%rcx
mov    %rdx,%rax
jl     1170 <main+0x40>
lea    0xe69(%rip),%rdi
mov    %rsp,%rsi
call   1040 <printf@plt>
xor    %eax,%eax
add    $0x1390,%rsp
pop    %rbx
ret

LLVM IR (-O0):
@stdin = global i32 0
@.str = [3 x i8] c"%s\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca [5000 x i8]
%3 = alloca i8
%4 = alloca i32
%5 = alloca i32
store i32 0, i32* %1
%6 = getelementptr inbounds [5000 x i8], [5000 x i8]* %2, i64 0, i64 0
%7 = load i32, i32* @stdin
%8 = call i32 @fgets(i8* %6, i32 5000, i32 %7)
%9 = getelementptr inbounds [5000 x i8], [5000 x i8]* %2, i64 0, i64 0
%10 = call i32 @strlen(i8* %9)
%11 = sub nsw i32 %10, 1
store i32 %11, i32* %5
store i32 0, i32* %4
br label %12
12: ; preds = %32, %0
%13 = load i32, i32* %4
%14 = load i32, i32* %5
%15 = icmp slt i32 %13, %14
br i1 %15, label %16, label %37
16: ; preds = %12
%17 = load i32, i32* %4
%18 = sext i32 %17 to i64
%19 = getelementptr inbounds [5000 x i8], [5000 x i8]* %2, i64 0, i64 %18
%20 = load i8, i8* %19
store i8 %20, i8* %3
%21 = load i32, i32* %5
%22 = sext i32 %21 to i64
%23 = getelementptr inbounds [5000 x i8], [5000 x i8]* %2, i64 0, i64 %22
%24 = load i8, i8* %23
%25 = load i32, i32* %4
%26 = sext i32 %25 to i64
%27 = getelementptr inbounds [5000 x i8], [5000 x i8]* %2, i64 0, i64 %26
store i8 %24, i8* %27
%28 = load i8, i8* %3
%29 = load i32, i32* %5
%30 = sext i32 %29 to i64
%31 = getelementptr inbounds [5000 x i8], [5000 x i8]* %2, i64 0, i64 %30
store i8 %28, i8* %31
br label %32
32: ; preds = %16
%33 = load i32, i32* %4
%34 = add nsw i32 %33, 1
store i32 %34, i32* %4
%35 = load i32, i32* %5
%36 = add nsw i32 %35, -1
store i32 %36, i32* %5
br label %12
37: ; preds = %12
%38 = getelementptr inbounds [5000 x i8], [5000 x i8]* %2, i64 0, i64 0
%39 = call i32 @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %38)
ret i32 0
}

LLVM IR (-O2):
@stdin = global i32 0
@.str = [3 x i8] c"%s\00"
define i32 @main() {
%1 = alloca [5000 x i8]
%2 = getelementptr inbounds [5000 x i8], [5000 x i8]* %1, i64 0, i64 0
%3 = load i32, i32* @stdin
%4 = call i32 @fgets(i8* %2, i32 5000, i32 %3)
%5 = call i32 @strlen(i8* %2)
%6 = icmp sgt i32 %5, 1
br i1 %6, label %7, label %20
7: ; preds = %0
%8 = zext i32 %5 to i64
%9 = add nsw i64 %8, -1
br label %10
10: ; preds = %7, %10
%11 = phi i64 [ 0, %7 ], [ %17, %10 ]
%12 = phi i64 [ %9, %7 ], [ %18, %10 ]
%13 = getelementptr inbounds [5000 x i8], [5000 x i8]* %1, i64 0, i64 %11
%14 = load i8, i8* %13
%15 = getelementptr inbounds [5000 x i8], [5000 x i8]* %1, i64 0, i64 %12
%16 = load i8, i8* %15
store i8 %16, i8* %13
store i8 %14, i8* %15
%17 = add nuw nsw i64 %11, 1
%18 = add nsw i64 %12, -1
%19 = icmp slt i64 %17, %18
br i1 %19, label %10, label %20
20: ; preds = %10, %0
%21 = call i32 @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %2)
ret i32 0
}