.data
prompt:
    .asciiz "Enter a nonnegative integer: "
msg:
    .asciiz "! = "

    .text
    .globl main

main:
    li $v0, 4
    la $a0, prompt
    syscall
    li $v0, 5
    syscall
    move $s0, $v0   # $s0 contains input number n

    move $a0, $v0
    li $v0, 1
    syscall
    li $v0, 4
    la $a0, msg
    syscall

    move $a0, $s0
    jal fact

    move $a0, $v0
    li $v0, 1
    syscall

    li $v0, 10
    syscall

fact:
    li $v0, 1
loop:    
    beqz $a0, done
    mul $v0, $v0, $a0
    addi $a0, $a0, -1
    j loop
done:
    jr $ra