#include #include #include #include //#include #include #include #include #include #include //#include #include #include #include //#include #include #include //#include #include #include #include #include const int dx[] = {1, 0, -1, 0}; const int dy[] = {0, 1, 0, -1}; using namespace std; //typedef long long ll; typedef __int128 ll; typedef vector vi; typedef vector vll; typedef pair pii; const int MAXN = 100; bool prime[MAXN]; bool done[MAXN][MAXN]; ll pow_mod(ll a, ll p, ll mod) { if (a == 0) return 0; if (p == 0) return 1; if (p == 1) return a; if (p%2) return a*pow_mod(a, p-1, mod)%mod; ll tmp = pow_mod(a, p/2, mod); return tmp*tmp&mod; } bool check(ll a, ll n, int k, ll q) { ll tmp = pow_mod(a, q, n); if (tmp == 1) return true; for (int i = 0; i < k-1; i++) { tmp = tmp*tmp%n; if (tmp == n-1) return true; if (tmp == 1) return false; } return false; } bool isPrime(ll n) { ll q = n-1; int k = 0; while (q%2==0) { q /= 2; k++; } vector p = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41}; for (ll a : p) { if (!check(a, n, k, q)) return false; } return true; } int main() { cin.tie(0); ios::sync_with_stdio(false); for (int i = 2; i < MAXN; i++) prime[i] = true; for (int i = 2; i < MAXN; i++) { if (prime[i]) for (int j = 2; j*i < MAXN; j++) prime[i*j] = false; } string s; cin >> s; ll N = 0; reverse(s.begin(), s.end()); for (char el : s) N = N*10+(el-'0'); if (N < 100) { for (int w = 2; w < N; w++) { int h = N/w+(N%w!=0); vector board(h, vi(w)); for (int j = 0; j < N; j++) { board[j/w][j%w] = j+1; } assert(board[(N-1)/w][(N-1)%w] == N); queue que; memset(done, false, sizeof(done)); que.push(pii(0, 0)); done[0][0] = true; while (!que.empty()) { pii p = que.front(); que.pop(); for (int k = 0; k < 4; k++) { int ny = p.first+dy[k]; int nx = p.second+dx[k]; if (ny < 0 || ny >= h || nx < 0 || nx >= w || board[ny][nx] == 0 || prime[board[ny][nx]]) continue; if (done[ny][nx]) continue; done[ny][nx] = true; que.push(pii(ny, nx)); } } if (done[(N-1)/w][(N-1)%w]) { cout << w << endl; return 0; } } } else { if (N%8 == 1 && isPrime(N-8)) cout << 14 << endl; else cout << 8 << endl; } return 0; }