#include using namespace std; typedef ostringstream OSS; typedef istringstream ISS; typedef long long LL; typedef pair PII; typedef vector VI; typedef vector VVI; typedef vector VLL; typedef vector VVLL; typedef vector VD; typedef vector VVD; typedef vector VS; typedef vector VVS; typedef vector VB; typedef vector VVB; typedef vector VPII; #define fst first #define snd second // #define Y first // #define X second #define MP make_pair #define PB push_back #define EB emplace_back #define ALL(x) (x).begin(),(x).end() #define RANGE(x,y,maxX,maxY) (0 <= (x) && 0 <= (y) && (x) < (maxX) && (y) < (maxY)) #define DUMP( x ) cerr << #x << " = " << ( x ) << endl #define rep(i, N) for (int i = 0; i < (int)(N); i++) #define REP(i, init, N) for (int i = (init); i < (int)(N); i++) template < typename T > inline T fromString(const string &s) { T res; ISS iss(s); iss >> res; return res; }; template < typename T > inline string toString(const T &a) { OSS oss; oss << a; return oss.str(); }; const int INF = 0x3f3f3f3f; const LL INFL = 0x3f3f3f3f3f3f3f3fLL; const double DINF = 0x3f3f3f3f; const int DX[]={1,0,-1,0},DY[]={0,-1,0,1}; const double EPS = 1e-12; //const double PI = acos(-1.0); int main(void) { LL N; cin >> N; for (LL i = 3; i * i <= N; i++) { if (!(N % i)) { cout << i << endl; return 0; } } if (!(N % 2)) { cout << (N / 2) << endl; } else { cout << N << endl; } return 0; }