#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 pow(int, int);
int /*<<< orphan*/ printf(char *, double);
int /*<<< orphan*/ scanf(char *, int *);
int sqrt(int);
int main() {
  int n;
  double f;
  scanf("%i", &n);
  f = (pow(((1 + sqrt(5)) / 2), n) - pow((1 - sqrt(5)) / 2, n)) / sqrt(5);
  printf("%.1f\n", f);
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
movl   $0x0,-0x4(%rbp)
lea    0xeaa(%rip),%rdi
lea    -0x8(%rbp),%rsi
call   1040 <scanf@plt>
mov    $0x5,%edi
call   1060 <sqrt@plt>
add    $0x1,%eax
mov    $0x2,%ecx
cltd
idiv   %ecx
mov    %eax,%edi
mov    -0x8(%rbp),%esi
call   1050 <pow@plt>
mov    %eax,-0x18(%rbp)
mov    $0x5,%edi
call   1060 <sqrt@plt>
mov    %eax,%ecx
mov    $0x1,%eax
sub    %ecx,%eax
mov    $0x2,%ecx
cltd
idiv   %ecx
mov    %eax,%edi
mov    -0x8(%rbp),%esi
call   1050 <pow@plt>
mov    %eax,%ecx
mov    -0x18(%rbp),%eax
sub    %ecx,%eax
mov    %eax,-0x14(%rbp)
mov    $0x5,%edi
call   1060 <sqrt@plt>
mov    %eax,%ecx
mov    -0x14(%rbp),%eax
cltd
idiv   %ecx
cvtsi2sd %eax,%xmm0
movsd  %xmm0,-0x10(%rbp)
movsd  -0x10(%rbp),%xmm0
lea    0xe2c(%rip),%rdi
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbx
sub    $0x10,%rsp
lea    0xeb4(%rip),%rdi
lea    0xc(%rsp),%rsi
call   1040 <scanf@plt>
mov    $0x5,%edi
call   1060 <sqrt@plt>
mov    %eax,%ecx
add    $0x1,%ecx
shr    $0x1f,%ecx
lea    (%rax,%rcx,1),%edi
add    $0x1,%edi
sar    %edi
mov    0xc(%rsp),%esi
call   1050 <pow@plt>
mov    %eax,%ebx
mov    $0x5,%edi
call   1060 <sqrt@plt>
mov    $0x1,%ecx
sub    %eax,%ecx
mov    %ecx,%edi
shr    $0x1f,%edi
add    %ecx,%edi
sar    %edi
mov    0xc(%rsp),%esi
call   1050 <pow@plt>
sub    %eax,%ebx
mov    $0x5,%edi
call   1060 <sqrt@plt>
mov    %eax,%ecx
mov    %ebx,%eax
cltd
idiv   %ecx
cvtsi2sd %eax,%xmm0
lea    0xe47(%rip),%rdi
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x10,%rsp
pop    %rbx
ret

LLVM IR (-O0):
@.str = [3 x i8] c"%i\00"
@.str.1 = [6 x i8] c"%.1f\0A\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca i32
%3 = alloca double
store i32 0, i32* %1
%4 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32* %2)
%5 = call i32 @sqrt(i32 5)
%6 = add nsw i32 1, %5
%7 = sdiv i32 %6, 2
%8 = load i32, i32* %2
%9 = call i32 @pow(i32 %7, i32 %8)
%10 = call i32 @sqrt(i32 5)
%11 = sub nsw i32 1, %10
%12 = sdiv i32 %11, 2
%13 = load i32, i32* %2
%14 = call i32 @pow(i32 %12, i32 %13)
%15 = sub nsw i32 %9, %14
%16 = call i32 @sqrt(i32 5)
%17 = sdiv i32 %15, %16
%18 = sitofp i32 %17 to double
store double %18, double* %3
%19 = load double, double* %3
%20 = call i32 @printf(i8* getelementptr inbounds ([6 x i8], [6 x i8]* @.str.1, i64 0, i64 0), double %19)
ret i32 0
}

LLVM IR (-O2):
@.str = [3 x i8] c"%i\00"
@.str.1 = [6 x i8] c"%.1f\0A\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 = call i32 @sqrt(i32 5)
%5 = add nsw i32 %4, 1
%6 = sdiv i32 %5, 2
%7 = load i32, i32* %1
%8 = call i32 @pow(i32 %6, i32 %7)
%9 = call i32 @sqrt(i32 5)
%10 = sub nsw i32 1, %9
%11 = sdiv i32 %10, 2
%12 = load i32, i32* %1
%13 = call i32 @pow(i32 %11, i32 %12)
%14 = sub nsw i32 %8, %13
%15 = call i32 @sqrt(i32 5)
%16 = sdiv i32 %14, %15
%17 = sitofp i32 %16 to double
%18 = call i32 @printf(i8* getelementptr inbounds ([6 x i8], [6 x i8]* @.str.1, i64 0, i64 0), double %17)
ret i32 0
}