// yukicoder 312 (http://yukicoder.me/problems/847)
#include<cstdio>
#include<algorithm>
#define rep(i,a) for(int i=0;i<(a);++i)

typedef long long ll;

ll N;

int main()
{
	scanf( "%lld", &N );

	ll ans = N&1?N:N/2!=2?N/2:N;
	for( ll i = 3; i*i <= N; ++i )
	{
		if( N % i == 0 )
		{ ans = std::min( ans, std::min( i, N/i ) ); break; }
	}

	printf( "%lld\n", ans );

	return 0;
}