#include <bits/stdc++.h>
#define GET_MACRO(a, b, c, NAME, ...) NAME
#define rep(...) GET_MACRO(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define rep2(i, a) rep3 (i, 0, a)
#define rep3(i, a, b) for (int i = (a); i < (b); i++)
#define repr(...) GET_MACRO(__VA_ARGS__, repr3, repr2)(__VA_ARGS__)
#define repr2(i, a) repr3 (i, 0, a)
#define repr3(i, a, b) for (int i = (b) - 1; i >= (a); i--)
using namespace std;
typedef long long ll;
template<class T1, class T2> inline bool chmin(T1 &a, T2 b) { return b < a && (a = b, true); }
template<class T1, class T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template<class T>
T parse(string s) {
	istringstream iss(s);
	T res;
	iss >> res;
	return res;
}

bool isprime(ll n) {
	for (ll i = 2; i * i <= n; i++) {
		if (n % i == 0) return false;
	}
	return n != 1;
}

bool check(int n, int w) {
	queue<pair<int, int>> q;
	vector<vector<char>> vis(n + 1, vector<char>(w));
	q.emplace(0, 0);
	vis[0][0] = true;
	n--;
	while (!q.empty()) {
		int y, x;
		tie(y, x) = q.front(); q.pop();
		int dy[] = {0, 1, 0, -1};
		int dx[] = {1, 0, -1, 0};
		rep (k, 4) {
			int ny = y + dy[k];
			int nx = x + dx[k];
			int nv = ny * w + nx;
			if (ny < 0 || nx < 0 || nx >= w || nv > n) continue;
			if (isprime(nv + 1)) continue;
			if (vis[ny][nx]) continue;
			vis[ny][nx] = true;
			q.emplace(ny, nx);
		}
	}
	return vis[n / w][n % w];
}

int main() {
	string N;
	cin >> N;
	if (N.length() >= 3) {
		cout << 8 << endl;
	} else {
		int n = parse<int>(N);
		int ans = 1;
		while (!check(n, ans)) ans++;
		cout << ans << endl;
	}
	return 0;
}