else if ( type_operation == "leave") {

            int s;

            in >> s;

            int le = l[s];

            int ri = r[s];

            if( l[s] != 0 || r[s] != 0 ){

            l[s] = 0;

            r[s] = 0;

            r[le] = ri;

            l[ri] = le;

            }