#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 check_prime(int);
int /*<<< orphan*/ printf(char *, int);
int /*<<< orphan*/ scanf(char *, int *);
int main() {
  int n;
  scanf("%d", &n);
  int count = 0;
  int i = 0;
  for (i = 0; i <= n - 2; i++) {
    if ((check_prime(i)) && (check_prime(i + 2)) == 1) {
      count++;
    }
  }
  printf("%d", count);
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
movl   $0x0,-0x4(%rbp)
lea    0xeba(%rip),%rdi
lea    -0x8(%rbp),%rsi
call   1050 <scanf@plt>
movl   $0x0,-0xc(%rbp)
movl   $0x0,-0x10(%rbp)
movl   $0x0,-0x10(%rbp)
mov    -0x10(%rbp),%eax
mov    -0x8(%rbp),%ecx
sub    $0x2,%ecx
cmp    %ecx,%eax
jg     11b6 <main+0x86>
mov    -0x10(%rbp),%edi
call   1030 <check_prime@plt>
cmp    $0x0,%eax
je     11a3 <main+0x73>
mov    -0x10(%rbp),%edi
add    $0x2,%edi
call   1030 <check_prime@plt>
cmp    $0x1,%eax
jne    11a3 <main+0x73>
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
jmp    11a8 <main+0x78>
mov    -0x10(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x10(%rbp)
jmp    1164 <main+0x34>
mov    -0xc(%rbp),%esi
lea    0xe40(%rip),%rdi
call   1040 <printf@plt>
xor    %eax,%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbp
push   %r14
push   %rbx
sub    $0x10,%rsp
lea    0xec1(%rip),%rdi
lea    0xc(%rsp),%rsi
call   1050 <scanf@plt>
xor    %r14d,%r14d
cmpl   $0x2,0xc(%rsp)
jge    116d <main+0x3d>
lea    0xea6(%rip),%rdi
mov    %r14d,%esi
call   1040 <printf@plt>
xor    %eax,%eax
add    $0x10,%rsp
pop    %rbx
pop    %r14
pop    %rbp
ret
xor    %r14d,%r14d
mov    $0xffffffff,%ebx
jmp    118d <main+0x5d>
nopw   0x0(%rax,%rax,1)
mov    0xc(%rsp),%eax
add    $0xfffffffe,%eax
mov    %ebp,%ebx
cmp    %eax,%ebp
jge    1153 <main+0x23>
lea    0x1(%rbx),%ebp
mov    %ebp,%edi
call   1030 <check_prime@plt>
test   %eax,%eax
je     1180 <main+0x50>
add    $0x3,%ebx
mov    %ebx,%edi
call   1030 <check_prime@plt>
xor    %ecx,%ecx
cmp    $0x1,%eax
sete   %cl
add    %ecx,%r14d
jmp    1180 <main+0x50>

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

LLVM IR (-O2):
@.str = [3 x i8] c"%d\00"
define i32 @main() {
%1 = alloca i32
%2 = bitcast i32* %1 to i8*
%3 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32* %1)
%4 = load i32, i32* %1
%5 = icmp slt i32 %4, 2
br i1 %5, label %23, label %6
6: ; preds = %0, %17
%7 = phi i32 [ %19, %17 ], [ 0, %0 ]
%8 = phi i32 [ %18, %17 ], [ 0, %0 ]
%9 = call i32 @check_prime(i32 %7)
%10 = icmp eq i32 %9, 0
br i1 %10, label %17, label %11
11: ; preds = %6
%12 = add nuw nsw i32 %7, 2
%13 = call i32 @check_prime(i32 %12)
%14 = icmp eq i32 %13, 1
%15 = zext i1 %14 to i32
%16 = add nsw i32 %8, %15
br label %17
17: ; preds = %11, %6
%18 = phi i32 [ %8, %6 ], [ %16, %11 ]
%19 = add nuw nsw i32 %7, 1
%20 = load i32, i32* %1
%21 = add nsw i32 %20, -2
%22 = icmp slt i32 %7, %21
br i1 %22, label %6, label %23
23: ; preds = %17, %0
%24 = phi i32 [ 0, %0 ], [ %18, %17 ]
%25 = call i32 @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32 %24)
ret i32 0
}