Valentine's Day Round 1002 Misaki's Kiss again

#include <iostream>
#include <iomanip>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <queue>
#include <vector>
#include <stack>
#include <string>
#include <cstring>
using namespace std;

typedef long long ll;
const int maxn=11111111;
const int INF=0x7fffffff;
const int mod=1e7+7;
#define LSON l,m,rt<<1
#define RSON m+1,r,rt<<1|1
#define ESP 1e-7

ll nc[55555], arr[55555];

int depart(ll x) {
    int k=0;
    for(ll i=1;i*i<=x;i++) {
        if(!(x%i)) {
            nc[k++]=i;
            if(i*i!=x)
                nc[k++]=x/i;
        }
    }
    return k;
}

ll gcd(ll a, ll b) {
    if(b==0) return a;
    return gcd(b, a%b);
}

int main() {
    ll n;
    int n_case=0;
    while(scanf("%lld", &n)!=EOF) {
        int sum=0;
        printf("Case #%d:\n", ++n_case);
        int tt=depart(n);
        for(int i=0;i<tt;i++) {
            ll m=n^nc[i];
            if(m>=1 && m<=n && gcd(n, m)==nc[i]) arr[sum++]=m;
        }
        sort(arr, arr+sum);
        printf("%d\n", sum);
        if(sum>0) {
            for(int i=0;i<sum-1;i++)
                printf("%lld ", arr[i]);
            printf("%lld\n", arr[sum-1]);
        }
        else printf("\n");
    }
    return 0;
}