int compress(vector<char>& chars) {
int k = 0, i = 0, j = 1;
chars.push_back(chars.back() + 1);
while(j < chars.size())
if(chars[j] == chars[i])
j++;
else {
chars[k++] = chars[i];
string dist = to_string(j - i);
i = j;
j = j + 1;
if(dist != "1")
for(char ch: dist)
chars[k++] = ch;
}
return k;
}