def generate combinations(digits,index,current,result,mapping):
    if index==len(digits):
        result.append(current)
        return 
    for ch in mapping[digits[index]]:
        generate combinations(digits,index +1, current +ch, result,mapping)
        
    digits = input().strip()
    
    if not digits.isdidgits():
        print("Invalid input")
        else:
            if  any(d < '2' or d > '9' for d in digits):
                print("Invalid input")
            else:
                mapping = {
                    '2': "ABC",
                    '3': "DEF",
                    '4': "GHI",
                    '5': "JKL",
                    '6': "MNO",
                    '7': "PQRS",
                    '8': "TUV",
                    '9': "WXYZ",
                    
                }
    
    result = []
    
    generate combinations(digits,0,"",result,mapping)
    print("[",end="")
    print(",".join(result),end="")
    print("]")