class Solution{
    public : 
        vector<string> readBinaryWatch(int turned On){
            vector<string> ans;
            for(int i =0;i<1024;i++){
                int h = i>>6, m = i & 63;
                if(h<12 && m<60 && __builtin_popcount(i) == turnedOn)
                    ans.push_back(to_string(h)+":"+(m<10?"0":"")+to_string(m));
            }
            return ans;
        }
}
//TC : o(1) as total number of enumerations will be independent of input size
//SC : o(1)