#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 *, ...);
int /*<<< orphan*/ scanf(char *, char *);
int strlen(char *);
int main() {
  char string[100];
  int counter, lenght;
  scanf("%s", string);
  printf("\n");
  lenght = strlen(string);
  for (counter = lenght - 1; counter >= 0; counter--) {
    printf("%c", string[counter]);
  }
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x80,%rsp
movl   $0x0,-0x4(%rbp)
lea    -0x70(%rbp),%rsi
lea    0xeb3(%rip),%rdi
call   1050 <scanf@plt>
lea    0xeaa(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
lea    -0x70(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,-0x78(%rbp)
mov    -0x78(%rbp),%eax
sub    $0x1,%eax
mov    %eax,-0x74(%rbp)
cmpl   $0x0,-0x74(%rbp)
jl     11a4 <main+0x74>
movslq -0x74(%rbp),%rax
movsbl -0x70(%rbp,%rax,1),%esi
lea    0xe76(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
mov    -0x74(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0x74(%rbp)
jmp    1175 <main+0x45>
mov    -0x4(%rbp),%eax
add    $0x80,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbx
sub    $0x70,%rsp
lea    0xec4(%rip),%rdi
mov    %rsp,%rbx
mov    %rbx,%rsi
call   1050 <scanf@plt>
mov    $0xa,%edi
call   1030 <putchar@plt>
mov    %rbx,%rdi
call   1040 <strlen@plt>
test   %eax,%eax
jle    1186 <main+0x56>
mov    %eax,%ebx
add    $0x1,%rbx
cs nopw 0x0(%rax,%rax,1)
nopl   (%rax)
lea    -0x2(%rbx),%eax
movsbl (%rsp,%rax,1),%edi
call   1030 <putchar@plt>
add    $0xffffffffffffffff,%rbx
cmp    $0x1,%rbx
ja     1170 <main+0x40>
xor    %eax,%eax
add    $0x70,%rsp
pop    %rbx
ret

LLVM IR (-O0):
@.str = [3 x i8] c"%s\00"
@.str.1 = [2 x i8] c"\0A\00"
@.str.2 = [3 x i8] c"%c\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca [100 x i8]
%3 = alloca i32
%4 = alloca i32
store i32 0, i32* %1
%5 = getelementptr inbounds [100 x i8], [100 x i8]* %2, i64 0, i64 0
%6 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i8* %5)
%7 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.1, i64 0, i64 0))
%8 = getelementptr inbounds [100 x i8], [100 x i8]* %2, i64 0, i64 0
%9 = call i32 @strlen(i8* %8)
store i32 %9, i32* %4
%10 = load i32, i32* %4
%11 = sub nsw i32 %10, 1
store i32 %11, i32* %3
br label %12
12: ; preds = %22, %0
%13 = load i32, i32* %3
%14 = icmp sge i32 %13, 0
br i1 %14, label %15, label %25
15: ; preds = %12
%16 = load i32, i32* %3
%17 = sext i32 %16 to i64
%18 = getelementptr inbounds [100 x i8], [100 x i8]* %2, i64 0, i64 %17
%19 = load i8, i8* %18
%20 = sext i8 %19 to i32
%21 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), i32 %20)
br label %22
22: ; preds = %15
%23 = load i32, i32* %3
%24 = add nsw i32 %23, -1
store i32 %24, i32* %3
br label %12
25: ; preds = %12
%26 = load i32, i32* %1
ret i32 %26
}

LLVM IR (-O2):
@.str = [3 x i8] c"%s\00"
define i32 @main() {
%1 = alloca [100 x i8]
%2 = getelementptr inbounds [100 x i8], [100 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 @putchar(i32 10)
%5 = call i32 @strlen(i8* %2)
%6 = icmp sgt i32 %5, 0
br i1 %6, label %7, label %18
7: ; preds = %0
%8 = zext i32 %5 to i64
br label %9
9: ; preds = %7, %9
%10 = phi i64 [ %8, %7 ], [ %11, %9 ]
%11 = add nsw i64 %10, -1
%12 = and i64 %11, 4294967295
%13 = getelementptr inbounds [100 x i8], [100 x i8]* %1, i64 0, i64 %12
%14 = load i8, i8* %13
%15 = sext i8 %14 to i32
%16 = call i32 @putchar(i32 %15)
%17 = icmp ugt i64 %10, 1
br i1 %17, label %9, label %18
18: ; preds = %9, %0
ret i32 0
}