#include<bits/stdc++.h>

using namespace std;
using ll = long long int;

int main(void) {
    constexpr ll MOD = 1e9 + 7;
    constexpr double PI = acos(-1);
    cout << fixed << setprecision(16);
    cin.tie(0); ios::sync_with_stdio(false);

    ll n;
    cin >> n;

    ll v[] = {101,131,151,181,191,211,241,251,271,281,311,331,401,421,431,461,491,521,541,571,601,631,641,661,691,701,751,761,811,821,881,911,941,971,991,1021,1031,1051,1061,1091,1151,1171,1181,1201,1231,1291,1301,1321,1361,1381,1451,1471,1481,1511,1531,1571,1601,1621,1721,1741,1801,1811,1831,1861,1871,1901,1931,1951,2011,2081,2111,2131,2141,2161,2221,2251,2281,2311,2341,2351,2371,2381,2411,2441,2521,2531,2551,2591};
    for(ll i=0; i<n; i++)
        cout << v[i] << ' ';
    cout << endl;
}

#include<bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using LL = long long;
using P = pair<int,int>;


int main(){
	string S;
	cin >> S;
	vector<bool> alpha(26);
	int N = S.size();
	string s = "abcdefghijklmnopqrstuvwxyz";
	rep(i,N){
		alpha[S[i] - 'a'] = true;
	}
	rep(i,26){
		if(alpha[i] == false){
			cout << s[i] << endl;
			return 0;
		}
	}
	 cout << "None" << endl;
	 return 0;
}










