.text
    .align 2
    .global main
    .global check
main:
    push {r4, r5, lr}
    mov r4, sp
loop:
    sub sp, #8
    bl getchar
    mov r5, r0
    bl check
    cmp r5, #-1
    mov sp, r4
    bne loop
    b return

return:
    pop {r4, r5, lr}
    bx  lr

check:
    push {lr}
    cmp r0, #57
    bxhi lr
    cmp r0, #48
    bxlO lr
    bl putchar
    pop {lr}
    bx lr

    .data
format:
    .asciz  "%d "