Vectors to store the lowercase and uppercase characters
vector < char > v1 , v2 ; for ( int i = 0 ; i < n ; i ++ ) { if ( s [ i ] >= ' a ' && s [ i ] <= ' z ' ) v1 . push_back ( s [ i ] ) ; if ( s [ i ] >= ' A ' && s [ i ] <= ' Z ' ) v2 . push_back ( s [ i ] ) ; }