#include
#include
#include
#include
#include
#include
#include
using namespace std;
#define REP(i,n) for(int i=0;i<(n);++i)
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define RFOR(i,a,b) for(int i=(a);i>=(b);--i)
typedef long long LL;
vector split( const string& s, const string& delim =" " ) {
vector res;
string t;
for ( int i = 0 ; i != s.size() ; i++ ) {
if ( delim.find( s[i] ) != string::npos ) {
if ( !t.empty() ) {
res.push_back( t );
t = "";
}
} else {
t += s[i];
}
}
if (!t.empty() ) {
res.push_back(t);
}
return res;
}
vector splitInt( const string& s, const string& delim =" " ) {
vector tok = split( s, delim );
vector res;
for ( int i = 0 ; i != tok.size(); i++ )
res.push_back( atoi( tok[i].c_str() ) );
return res;
}
LL gcd(LL a,LL b){
return b?gcd(b,a%b):a;
}
inline LL lcm(LL a,LL b){
return a/gcd(a,b)*b;
}
int s2i(string s) {
stringstream ss;
ss << s;
int res;
ss >> res;
return res;
}
string i2s(int n) {
stringstream ss;
ss << n;
string res;
ss >> res;
return res;
}
#define MAXN 1000000
int plist[80000],pcount=0;
int prime(int n){
int i;
if ((n!=2&&!(n%2))||(n!=3&&!(n%3))||(n!=5&&!(n%5))||(n!=7&&!(n%7)))
return 0;
for (i=0;plist[i]*plist[i]<=n;i++)
if (!(n%plist[i]))
return 0;
return n>1;
}
void initprime(){
int i;
for (plist[pcount++]=2,i=3;i<1000000;i++)
if (prime(i))
plist[pcount++]=i;
}
LL mm[MAXN + 1];
void run() {
initprime();
FOR(i,2,MAXN) mm[i] = i;
REP(i,pcount) {
int p = plist[i];
for (int s = p; s <= MAXN; s += p) {
mm[s] = mm[s] * (p - 1) / p;
}
}
double mx = 1.0;
int idx = 1;
FOR(i,2,MAXN) {
double tmp = i * 1.0 / mm[i];
if (tmp > mx) {
mx = tmp;
idx = i;
}
//cout << i << " " << mm[i] << endl;
}
cout << idx << endl;
}
int main() {
run();
}