s = list(input())
t = input()
n = len(s)-1
while (s[n] == 'z'):
s[n]='a'
n -= 1
s[n] = chr(ord(s[n])+1)
r =''.join(s)
if(r >= t):
print('No such string')
else:
print(r)#include<iostream>
#include<string>
#include<algorithm>
#include<cmath>
#include<vector>
#include<stack>
#include<set>
#include<map>
#include<queue>
#include <iomanip>
#include <bitset>
using namespace std;
#define ll long long
ll gcd(ll a, ll b) { return ((b == 0) ? a : gcd(b, a % b)); }
ll lcm(ll a, ll b) { return (b / gcd(a, b)) * a; }
void hhh() {
// freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr), cout.tie(nullptr);
}
void solve() {
string s, t;
cin >> s >> t;
int i = s.size() - 1;
while (i >= 1 && s[i] == 'z') {
s[i--] = 'a';
}
s[i]++;
if (s < t) {
cout << s;
}
else {
cout << "No such string";
}
}
int main() {
hhh();
solve();
return 0;
}1630C - Paint the Middle | 1630D - Flipping Range |
1328A - Divisibility Problem | 339A - Helpful Maths |
4A - Watermelon | 476A - Dreamoon and Stairs |
1409A - Yet Another Two Integers Problem | 977A - Wrong Subtraction |
263A - Beautiful Matrix | 180C - Letter |
151A - Soft Drinking | 1352A - Sum of Round Numbers |
281A - Word Capitalization | 1646A - Square Counting |
266A - Stones on the Table | 61A - Ultra-Fast Mathematician |
148A - Insomnia cure | 1650A - Deletions of Two Adjacent Letters |
1512A - Spy Detected | 282A - Bit++ |
69A - Young Physicist | 1651A - Playoff |
734A - Anton and Danik | 1300B - Assigning to Classes |
1647A - Madoka and Math Dad | 710A - King Moves |
1131A - Sea Battle | 118A - String Task |
236A - Boy or Girl | 271A - Beautiful Year |