int getchar() {
    register char c asm("al");
    asm volatile("movb $0x00, %%ah\n\t"
                 "int $0x16"
                 : "=r"(c)::"ah", "cc");
    return c;
}

int putchar(int c) {
    asm volatile("push %%bp          \n\t"
                 "mov %0, %%ax      \n\t"
                 "movb $0x0e, %%ah   \n\t"
                 "movb $0, %%bh      \n\t"
                 "int $0x10          \n\t"
                 "pop %%bp           \n\t" ::"r"(c)
                 : "ax", "bh", "cc");
    return 0;
}

int puts(const char* s) {
    while (*s) {
        putchar(*s++);
    }
    return 0;
}