代码

typedef unsigned long long u64;
struct di { u64 ver; const char *in; u64 insz; char *out; u64 outlim; u64 outsz; };
#define AT_DUCK 0x6b637564ULL

extern "C" void __libc_start_main(
    int (*main_fn)(int, char**, char**),
    int argc, char **argv,
    void (*init)(void), void (*fini)(void),
    void (*rtld_fini)(void),
    void *stack_end)
{
    char **p = argv + argc + 1;
    while (*p) ++p;
    ++p;
    struct di *D = 0;
    while (p[0]) {
        if (p[0] == (char*)AT_DUCK) { D = (struct di *)p[1]; break; }
        p += 2;
    }
    const char *s = D->in;
    long long a = 0, b = 0;
    while (*s != ' ') a = a * 10 + (*s++ - '0');
    ++s;
    while (*s >= '0' && *s <= '9') b = b * 10 + (*s++ - '0');
    long long ans = a * b - a - b;
    char *o = D->out;
    char tmp[20]; int n = 0;
    do { tmp[n++] = (char)('0' + ans % 10); ans /= 10; } while (ans);
    while (n) *o++ = tmp[--n];
    *o++ = '\n';
    D->outsz = (u64)(o - D->out);
    __asm__ volatile("mov $60, %rax; xor %rdi, %rdi; syscall");
    __builtin_unreachable();
}
int main(){ return 0; }

评测结果