// returns true iff string key is contained in string sentence
bool isPartOf(char* key, char* sentence){
    char *it=key, *s=sentence, *start=s;
    while(true){
        if(!*it){ return true; }
        if(!*s){ return false; }
        *it != *s ? (it=key,start++,s=start) : (it++,s++);
    }
}