#include #define endl '\n'; #define rep(i,n) for(int i=0; i<(n); i++) using namespace std; using ll = long long; using P = pair; #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native") #pragma GCC optimize("Ofast") constexpr ll INF = 1e18; constexpr int inf = 1e9; constexpr double INFD = 1e100; constexpr ll mod = 1000000007; constexpr ll mod2 = 998244353; const double PI = 3.1415926535897932384626433832795028841971; const int dx[4] = {1, 0, -1, 0}; const int dy[4] = {0, 1, 0, -1}; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } // ios::sync_with_stdio(false); // cin.tie(nullptr); // --------------------------------------------------------------------------- struct Sieve{ int n; vector f,primes; Sieve(int n=1):n(n),f(n+1){ f[0] = f[1] = -1; for(ll i=2; i<=n; i++){ if(f[i]) continue; primes.push_back(i); f[i] = i; for(ll j=i*i; j<=n; j+=i){ if(!f[j]) f[j] = i; } } } bool isPrime(int x){ return f[x] == x;} vector factorList(int x){ vector res; while(x != 1){ res.push_back(f[x]); x /= f[x]; } return res; } vector

factor(int x){ vector fl = factorList(x); if(fl.size() == 0) return { }; vector

res(1, P(fl[0],0)); for(int p : fl){ if(res.back().first == p){ res.back().second++; }else{ res.emplace_back(p,1); } } return res; } }; Sieve sieve(1e6); int f(int x){ int res = 1; for(auto s: sieve.factor(x)){ res *= s.second+1; } return res; } int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); int N; cin >> N; int dif = inf; vector vec(1e6); for(int i=1; i<=N-1; i++){ vec[i] = f(i); } for(int i=1; i<=N-1; i++){ int a=i,b=N-i; a -= vec[i]; b -= vec[N-i]; chmin(dif,abs(a-b)); } vector

ans; for(int i=1; i