#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)
typedef long long LL;
string i2s(int n) {
stringstream ss;
ss << n;
string res;
ss >> res;
return res;
}
LL s2ll(string str) {
stringstream ss;
ss << str;
LL res;
ss >> res;
return res;
}
int res;
bool isPrime(int n) {
int mid = (int) sqrt(n + 0.5);
for (int i = 3; i <= mid; i += 2) {
if (n % i == 0) return false;
}
return true;
}
void doit(int n) {
vector mm;
FOR(i,1,n) mm.push_back(i);
do {
if ((mm[n - 1] & 1) == 0 || mm[n - 1] == 5) continue;
int t = 0;
REP(i,n) t = t * 10 + mm[i];
if (isPrime(t)) res = max(res, t);
} while (next_permutation(mm.begin(), mm.end()));
}
void run() {
res = 2143;
doit(4);
doit(7);
doit(8);
cout << res << endl;
}
int main() {
run();
return 0;
}