"from collections import Counter

def isValid(s):
    counter_s = Counter(s)
    frequency = Counter(counter_s.values())

    if len(frequency) == 1:
        return ""YES""

    if len(frequency) == 2:
        key1, key2 = frequency.keys()
        val1, val2 = frequency[key1], frequency[key2]

        # Case A: one char has freq=1 and it appears once
        if (key1 == 1 and val1 == 1) or (key2 == 1 and val2 == 1):
            return ""YES""

        # Case B: frequencies differ by 1 and higher one appears once
        if abs(key1 - key2) == 1 and (frequency[max(key1, key2)] == 1):
            return ""YES""

    return ""NO""
"

Map<Character,Integer> ma=new HashMap<>();

        for(int i=0;i<s.length();i++)
        {
            if(!ma.containsKey(s.charAt(i)))
            {
                ma.put(s.charAt(i),1);
            }
            else {
                ma.computeIfPresent(s.charAt(i),(k,v)->++v);
            }
        }

         Integer[] op= ma.values().toArray(Integer[]::new);

        Arrays.sort(op);

        if(op[0]==op[op.length-1])
        {
            return "YES";
        }
  if(op[0]==1 && op[1]==op[op.length-1])
        {
           return "YES";
        }
       
            if(op[0]==op[1] && op[1]==op[op.length-2] && (op[1]==op[op.length-1]-1))
            {
                return "YES";
            }
        
    

return "NO";
    }

def isValid(s):
    counts_dict = {}
    for c in s:
        counts_dict[c] = counts_dict.get(c,0) + 1
    
    counts = counts_dict.values()
    counts_len = len(counts)
    min_num = min(counts)
    max_num = max(counts)
    counts_sum = sum(counts)
    
    return "YES" if min_num*counts_len == counts_sum or min_num*counts_len+1 == counts_sum or max_num*(counts_len-1)+1==counts_sum else "NO"

string isValid(string s) {
    std::map<char, int> uniq;
    for (const char c : s) {
        uniq[c]++;
    }
    auto max = std::max_element(uniq.begin(), uniq.end(), 
        [](std::pair<char, int> el1, std::pair<char, int> el2){
             return el1.second < el2.second;
             });
    auto min = std::min_element(uniq.begin(), uniq.end(),
        [](std::pair<char, int> el1, std::pair<char, int> el2){
             return el1.second < el2.second;
             });

    if (std::all_of(uniq.begin(), uniq.end(), [max](const auto el){ return el.second == max->second; } )) {
        return "YES";
    }
    max->second--;
    if (std::all_of(uniq.begin(), uniq.end(), [min](const auto el){ return el.second == min->second; } )) {
        return "YES";
    }
    max->second++;
    min->second--;
    if (std::all_of(uniq.begin(), uniq.end(), [max](const auto el){ return el.second == max->second || el.second == 0; } )) {
        return "YES";
    }
    return "NO";
}