def isValid(s):
    # Write your code here
    stringDict={}
    
    for letter in s:
        stringDict[letter]= stringDict.get(letter,0) + 1 
    dictValues= list(stringDict.values())
    isRemovedOne=False
    for i in range(1,len(dictValues)):
        diff= abs(dictValues[i]- dictValues[i-1])
        if  diff == 0:
            continue
        else:
            if not isRemovedOne:
                isRemovedOne=True
                dictValues[i]-=1
            else:
                return "NO"
    return "YES"

def isValid(s):
    cts=Counter(s) #Count occurences of string
    ct2=Counter(cts.values()) #Count unique occurences of string occurences
    #if only one item in ct2 then all occurences are equal, 
    #if two items then check if diff is 1 and second most has a count of 1
    #Special case: if the second occurences of occurences equals 1, 
    #it means the second 1 occurrence can be removed to make a valid string.
    kc=ct2.most_common()
    return 'YES' if len(kc)==1 or (len(kc)==2 and \
     (((kc[1][0]-kc[0][0])==1 or kc[1][0]==1) and kc[1][1]==1)) else 'NO'

def isValid(s):
    # Write your code here
    holder = {}
    for char in s:
        if char in holder:
            holder[char] += 1
        else:
            holder[char] = 1
    val = list(holder.values())
    val.sort()
    test1 = set(val[1:])
    test2 = set(val[:-1])
    test2.add(val[-1]-1)
    result = "YES" if len(test1) == 1 or len(test2) == 1 else "NO"
    return result