string timeConversion(string s) {
string hour= s.substr(0,2);
string ms= s.substr(2,6);
string meridian= s.substr(8,2);
int clock = stoi(hour);
if(meridian=="AM")
{
    if(clock==12)
    {
        hour="00";
    }
}
else if(meridian =="PM")
{
    if(hour!="12")
    {
        clock+=12;
        hour  =to_string(clock);
    }
}
return hour+ms;
}