CF 518A(Vitaly and Strings-构造)

A. Vitaly and Strings

time limit per test

memory limit per test

input

output

Vitaly is a diligent student who never missed a lesson in his five years of studying in the university. He always does his homework on time and passes his exams in time.

s and t to Vitaly. The strings have the same length, they consist of lowercase English letters, string s is lexicographically smaller than string t. Vitaly wondered if there is such string that is lexicographically larger than string s and at the same is lexicographically smaller than string t. This string should also consist of lowercase English letters and have the length equal to the lengths of strings s and t.

Let's help Vitaly solve this easy problem!

Input

s (1 ≤ |s| ≤ 100), consisting of lowercase English letters. Here, |s|

t (|t| = |s|), consisting of lowercase English letters.

s and t are the same and string s is lexicographically less than string t.

Output

No such string" (without the quotes).

If such string exists, print it. If there are multiple valid strings, you may print any of them.

Sample test(s)

input

a c

output

b

input

aaa zzz

output

kkk

input

abcdefg abcdefh

output

No such string

Note

s = s1s2... sn is said to be lexicographically smaller than t = t1t2... tn, if there exists such i, that s1 = t1, s2 = t2, ... si - 1 = ti - 1, si < ti.

 确定s的下一个序列是否<t,注意‘z'

az<ba<bb

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<functional>
#include<iostream>
#include<cmath>
#include<cctype>
#include<ctime>
using namespace std;
#define For(i,n) for(int i=1;i<=n;i++)
#define Fork(i,k,n) for(int i=k;i<=n;i++)
#define Rep(i,n) for(int i=0;i<n;i++)
#define ForD(i,n) for(int i=n;i;i--)
#define RepD(i,n) for(int i=n;i>=0;i--)
#define Forp(x) for(int p=pre[x];p;p=next[p])
#define Forpiter(x) for(int &p=iter[x];p;p=next[p])  
#define Lson (x<<1)
#define Rson ((x<<1)+1)
#define MEM(a) memset(a,0,sizeof(a));
#define MEMI(a) memset(a,127,sizeof(a));
#define MEMi(a) memset(a,128,sizeof(a));
#define INF (2139062143)
#define F (100000007)
#define MAXN (100+10)
long long mul(long long a,long long b){return (a*b)%F;}
long long add(long long a,long long b){return (a+b)%F;}
long long sub(long long a,long long b){return (a-b+(a-b)/F*F+F)%F;}
typedef long long ll;
char s[MAXN],t[MAXN];
int main()
{
//  freopen("a.in","r",stdin);
//  freopen(".out","w",stdout);
  scanf("%s%s",s,t);
  
  int n=strlen(s);
  
  s[n-1]++;
  RepD(i,n-1)
  {
    if (s[i]>'z')
    {
      s[i]='a';
      if (i>0) s[i-1]++;
      else
      {
        cout<<"No such string\n";
        return 0;
      }
    } 
  } 
  
  bool flag=0;
  Rep(i,n)
  {
    if (s[i]==t[i]) continue;
    else if (s[i]<t[i]) {flag=1;break;}
    else 
    {
      cout<<"No such string\n";
      return 0;
    }
  }
  
  if (flag) printf("%s\n",s);
  else cout<<"No such string\n";
  
    
  
  return 0;
}