Problem - 1514C - Codeforces

题意：

 

思路：

Code：

#include <bits/stdc++.h>using i64 = long long;constexpr int N = 2e5 + 10;
constexpr int M = 2e5 + 10;
constexpr int mod = 998244353;void solve() {int n;std::cin >> n;std::vector<int> ans;i64 mul = 1ll;for (int i = 1; i <= n - 1; i ++) {if (std::__gcd(i, n) == 1) {ans.push_back(i);mul *= i;mul %= n;}}if (mul == 1ll) {std::cout << ans.size() << "\n";for (int i = 0; i < ans.size(); i ++) {std::cout << ans[i] << " \n" [i == ans.size() - 1];}}else {std::cout << ans.size() - 1 << "\n";for (int i = 0; i < ans.size() - 1; i ++) {if (ans[i] != n) {std::cout << ans[i] << " "; }}std::cout << "\n";}
}
signed main() {std::ios::sync_with_stdio(false);std::cin.tie(nullptr);int t = 1;while(t --) {solve();}return 0;
}