#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*/ printf(char *, char *);
int /*<<< orphan*/ scanf(char *, char *);
int strlen(char *);
int main() {
  char str[50], rts = 0;
  int k = 0, n = 0;
  scanf("%s", str);
  n = strlen(str) - 1;
  while (k < n) {
    rts = str[k];
    str[k] = str[n];
    str[n] = rts;
    k++;
    n--;
  }
  printf("%s", str);
  return (0);
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x50,%rsp
movl   $0x0,-0x4(%rbp)
movb   $0x0,-0x41(%rbp)
movl   $0x0,-0x48(%rbp)
movl   $0x0,-0x4c(%rbp)
lea    -0x40(%rbp),%rsi
lea    0xea4(%rip),%rdi
call   1050 <scanf@plt>
lea    -0x40(%rbp),%rdi
call   1030 <strlen@plt>
sub    $0x1,%eax
mov    %eax,-0x4c(%rbp)
mov    -0x48(%rbp),%eax
cmp    -0x4c(%rbp),%eax
jge    11b9 <main+0x89>
movslq -0x48(%rbp),%rax
mov    -0x40(%rbp,%rax,1),%al
mov    %al,-0x41(%rbp)
movslq -0x4c(%rbp),%rax
mov    -0x40(%rbp,%rax,1),%cl
movslq -0x48(%rbp),%rax
mov    %cl,-0x40(%rbp,%rax,1)
mov    -0x41(%rbp),%cl
movslq -0x4c(%rbp),%rax
mov    %cl,-0x40(%rbp,%rax,1)
mov    -0x48(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x48(%rbp)
mov    -0x4c(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0x4c(%rbp)
jmp    1170 <main+0x40>
lea    -0x40(%rbp),%rsi
lea    0xe3c(%rip),%rdi
call   1040 <printf@plt>
xor    %eax,%eax
add    $0x50,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbx
sub    $0x40,%rsp
lea    0xec4(%rip),%rdi
mov    %rsp,%rbx
mov    %rbx,%rsi
call   1050 <scanf@plt>
mov    %rbx,%rdi
call   1030 <strlen@plt>
cmp    $0x2,%eax
jl     1180 <main+0x50>
mov    %eax,%eax
add    $0xfffffffffffffffe,%rax
xor    %ecx,%ecx
nopl   0x0(%rax)
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     1160 <main+0x30>
lea    0xe79(%rip),%rdi
mov    %rsp,%rsi
call   1040 <printf@plt>
xor    %eax,%eax
add    $0x40,%rsp
pop    %rbx
ret

LLVM IR (-O0):
@.str = [3 x i8] c"%s\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca [50 x i8]
%3 = alloca i8
%4 = alloca i32
%5 = alloca i32
store i32 0, i32* %1
store i8 0, i8* %3
store i32 0, i32* %4
store i32 0, i32* %5
%6 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 0
%7 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %6)
%8 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 0
%9 = call i32 @strlen(i8* %8)
%10 = sub nsw i32 %9, 1
store i32 %10, i32* %5
br label %11
11: ; preds = %15, %0
%12 = load i32, i32* %4
%13 = load i32, i32* %5
%14 = icmp slt i32 %12, %13
br i1 %14, label %15, label %35
15: ; preds = %11
%16 = load i32, i32* %4
%17 = sext i32 %16 to i64
%18 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 %17
%19 = load i8, i8* %18
store i8 %19, i8* %3
%20 = load i32, i32* %5
%21 = sext i32 %20 to i64
%22 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 %21
%23 = load i8, i8* %22
%24 = load i32, i32* %4
%25 = sext i32 %24 to i64
%26 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 %25
store i8 %23, i8* %26
%27 = load i8, i8* %3
%28 = load i32, i32* %5
%29 = sext i32 %28 to i64
%30 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 %29
store i8 %27, i8* %30
%31 = load i32, i32* %4
%32 = add nsw i32 %31, 1
store i32 %32, i32* %4
%33 = load i32, i32* %5
%34 = add nsw i32 %33, -1
store i32 %34, i32* %5
br label %11
35: ; preds = %11
%36 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 0
%37 = call i32 @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %36)
ret i32 0
}

LLVM IR (-O2):
@.str = [3 x i8] c"%s\00"
define i32 @main() {
%1 = alloca [50 x i8]
%2 = getelementptr inbounds [50 x i8], [50 x i8]* %1, i64 0, i64 0
%3 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %2)
%4 = call i32 @strlen(i8* %2)
%5 = icmp sgt i32 %4, 1
br i1 %5, label %6, label %19
6: ; preds = %0
%7 = zext i32 %4 to i64
%8 = add nsw i64 %7, -1
br label %9
9: ; preds = %6, %9
%10 = phi i64 [ 0, %6 ], [ %16, %9 ]
%11 = phi i64 [ %8, %6 ], [ %17, %9 ]
%12 = getelementptr inbounds [50 x i8], [50 x i8]* %1, i64 0, i64 %10
%13 = load i8, i8* %12
%14 = getelementptr inbounds [50 x i8], [50 x i8]* %1, i64 0, i64 %11
%15 = load i8, i8* %14
store i8 %15, i8* %12
store i8 %13, i8* %14
%16 = add nuw nsw i64 %10, 1
%17 = add nsw i64 %11, -1
%18 = icmp slt i64 %16, %17
br i1 %18, label %9, label %19
19: ; preds = %9, %0
%20 = call i32 @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %2)
ret i32 0
}