public bool refine(string s, int min_prefix_size=1)
{
size_t len;
- for (len = 0; prefix[len] != 0 && s[len] != 0 && s[len] == prefix[len]; ++len)
+ for (len = 0; prefix[(long)len] != 0 && s[(long)len] != 0 && s[(long)len] == prefix[(long)len]; ++len)
;
if (len < min_prefix_size) return false;
if (len != pfx_len)