#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <complex>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <iomanip>
#include <assert.h>
#include <array>
#include <cstdio>
#include <cstring>
#include <random>
#include <functional>
#include <numeric>
#include <bitset>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)
#define all(c) (c).begin(), (c).end()
#define zero(a) memset(a, 0, sizeof a)
#define minus(a) memset(a, -1, sizeof a)
#define minimize(a, x) a = std::min(a, x)
#define maximize(a, x) a = std::max(a, x)

typedef long long ll;
int const inf = 1<<29;

namespace math {
namespace prime {

constexpr int Max = 364364;

int prime[Max];
bool is_prime[Max];

int sieve(int n) {
  int prime_count = 0;
  rep(i, n+1) is_prime[i] = 1;
  is_prime[0] = is_prime[1] = 0;
  REP(i, 2, n+1) {
    if(!is_prime[i]) { continue; }
    prime[prime_count++] = i;
    for(long long j=(long long)i*i; j<=n; j+=i) {
      is_prime[j] = 0;
    }
  }
  return prime_count;
}

}
}

int main() {
  using namespace math::prime;
  sieve(114514);
  int n; cin >> n;
  if(is_prime[n-100]) {
    if(is_prime[n-99]) {
      cout << n-98 << endl;
    }
    else {
      cout << n-99 << endl;
    }
  }
  else {
    cout << n-100 << endl;
  }

  return 0;
}