.globl main
main:   mv s0, a0
        addi sp, sp, -48
        sd s0, 0(sp)
        addi a0, s0, -4
        bnez a0, 1f
        li a0, -1
        j 2f
1:      li a0, 0
2:      ld s0, 0(sp)
        addi sp, sp, 48
        ret