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 (*m)(int,char**,char**), int argc, char **argv,
    void (*i)(void), void (*f)(void), void (*r)(void), void *se)
{
    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;
    unsigned long long a=0,b=0;
    while (*s!=' ') a=a*10+(*s++-'0'); ++s;
    while (*s>='0'&&*s<='9') b=b*10+(*s++-'0');
    unsigned long long ans=a*b-a-b;
    char *o=D->out, *st=o;
    do { *o++ = '0'+ans%10; ans/=10; } while(ans);
    *o++='\n';
    char *e=o-2;
    while(st<e){char t=*st;*st=*e;*e=t;++st;--e;}
    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