SC:     .string "%d%d%d%d"
PR:     .string "%d\n"

        .text
        .global process

step:
        pushl   %ebp
        pushl   %ebx
        mov     %esp, %ebp
        sub     $36, %esp

        lea     32(%esp), %eax
        lea     28(%esp), %ebx
        lea     24(%esp), %ecx
        lea     20(%esp), %edx
        mov     %eax, 16(%esp)
        mov     %ebx, 12(%esp)
        mov     %ecx, 8(%esp)
        mov     %edx, 4(%esp)
        movl    $SC, (%esp)

        call    scanf
        cmpl    $4, %eax
        jne     STEP_FINISH

        movl    32(%esp), %edx
        movl    28(%esp), %ecx
        movl    24(%esp), %ebx
        movl    20(%esp), %eax

        cmp     %eax, %ecx
        jb      STEP_LEFT
        mov     %ecx, %eax

STEP_LEFT:
        cmp     %ebx, %edx
        ja      STEP_RIGHT
        mov     %edx, %ebx

STEP_RIGHT:
        sub     %eax, %ebx
        jns     STEP_PRINT
        mov     $0, %ebx

STEP_PRINT:
        addl    %ebx, %esi
        xor     %eax, %eax
        jmp     STEP_EXIT

STEP_FINISH:
        movl    $1, %eax

STEP_EXIT:
        mov     %ebp, %esp
        popl    %ebx
        popl    %ebp
        ret

process:
        pushl   %ebp
        pushl   %esi
        mov     %esp, %ebp
        andl    $-16, %esp
        xor %esi, %esi

body:
        call    step

        movl    %esi, 4(%esp)
        movl    $PR, (%esp)
        call    printf

        test    %eax, %eax
        jz  body

        mov     %ebp, %esp
        popl    %esi
        popl    %ebp
        xor     %eax, %eax
        ret

        .global main
main:
        call    process
        ret