https://clickhouse-test-reports.s3.yandex.net/17375/99073c26ee2692f8efe2ab14b2d8ae0fd813b80e/fuzzer/fuzzer.log

```
SELECT
    k,
    topK(v)
FROM 
(
    SELECT
        number % 7 AS k,
        arrayMap(x -> arrayMap(x -> if(x = 0, NULL, toString(x)), range(x)), range(intDiv(number, 1))) AS v
    FROM system.numbers
    LIMIT 257
)
GROUP BY k
ORDER BY k ASC
```
{
private:
    
    
    constexpr uint64_t nextAlphaSize(uint64_t x)
    {
        constexpr uint64_t ALPHA_MAP_ELEMENTS_PER_COUNTER = 6;
        return 1ULL << (sizeof(uint64_t) * 8 - __builtin_clzll(x * ALPHA_MAP_ELEMENTS_PER_COUNTER));
    }
public:
    using Self = SpaceSaving;
    struct Counter
    {
        Counter() {}
        Counter(const TKey & k, UInt64 c = 0, UInt64 e = 0, size_t h = 0)
          : key(k), slot(0), hash(h), count(c), error(e) {}
        void write(WriteBuffer & wb) const