Problem: A subsequence of a string S is a string that can be obtained by deleting zero or more characters from S without changing the order of the remaining characters. For example, `arc`, `artistic` and (an empty string) are all subsequences of `artistic`; `abc` and `ci` are not.  You are given a string A consisting of lowercase English letters. Find the shortest string among the strings consisting of lowercase English letters that are not subsequences of A. If there are more than one such string, find the lexicographically smallest one among them.

Submission attempts (in order):
def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
            memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
            memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1

    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1

    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            memo[i][y]=memo[i+1][y]

    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            memo[i][y]=memo[i+1][y]

    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
            memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
            memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1

    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1

    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            memo[i][y]=memo[i+1][y]

    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            memo[i][y]=memo[i+1][y]

    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():  
            memo[i][y]=memo[i+1][y]
        memo[i][alpha2[s[i]]]=i+1
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            if s[i]==x:
                memo[i][y]=i+1
            else:
                memo[i][y]=memo[i+1][y]
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            if s[i]==x:
                memo[i][y]=i+1
            else:
                memo[i][y]=memo[i+1][y]
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            if s[i]==x:
                memo[i][y]=i+1
            else:
                memo[i][y]=memo[i+1][y]
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

def main():
    import sys
    input=sys.stdin.readline
    s=input()
    alpha="abcdefghijklmnopqrstuvwxyz"
    l=len(s)
    alpha2={j:i for i,j in enumerate(alpha)}
    memo=[[0]*26 for _ in range(l,-1,-1)]
    for i in range(26):
        memo[l][i]=l+1
    for i in range(l-1,-1,-1):
        for x,y in alpha2.items():
            if s[i]==x:
                memo[i][y]=i+1
            else:
                memo[i][y]=memo[i+1][y]
    
    search=[1]*(l+2)
    search[l+1]=0
    for i in range(l-1,-1,-1):
        m=max([memo[i][j] for j in range(26)])
        if m!=l+1:
            search[i]=search[m]+1
    
    n,seq=0,0
    ans_len=search[0]
    ans=""
    temp=0
    for i in range(ans_len):
        for j in range(26):
            n=memo[temp][j]
            seq=search[n]+i
            if seq+1==ans_len:
                ans+=alpha[j]
                temp=memo[temp][j]
                break
    print(ans)
if __name__=='__main__':
    main()

Verdicts: Runtime Error

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Runtime Error

Runtime Error

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Accepted

Accepted