map<string,int> q;
int c, i, n, x=1;
auto countAtoms(auto M) {
    for (i=size(M); ~--i;)
        c=M[i],
        c == '(' ?
            x=1, n=0
         : c == ')' ?
            x=n+!n, n=0
        : isdigit(c) ?
            n = n*10 + c-48
        : isupper(c) ?
            q[{c}] += x*(n+!n), n=0
        : islower(c) ?
            q[{M[--i], c}] += x*(n+!n), n=0
        : 0;
    M="";
    for (auto [k,v] : q)
          M += k + to_string(v);
    return M;
}