mov %rsp,%r9
read:
    mov $0,%rax
    mov $0,%rbx
    mov %rsp,%rcx
    mov $1,%rdx
    syscall
    add $8,%rsp
    cmp $0,%rax
    jne read
    mov %rsp,%r8
    sub %r9,%r8
    movq $1,%rax
    movq $1,%rsi
    movq %rsp,%rsi
    movq %r8,%rdx
    syscall
    movq    $60, %rax
    movq    $0, %rdi
    syscall