/*
 * insert list
 */

int insertList(list l, int data){
     list lD, t;

     lD = (list)malloc(sizeof(node));
     if(lD == NULL) return 0;
     lD->data = data;
     if(isEmptyList(l)) {
        lD->rP = NULL;
        lD->lP = l;
        l->rP = lD;
        return 1;
     }
     else {
         t = l->rP;
         while(t->rP && t->data < data) t = t->rP;
         if(t->data == data) { free(lD); return 0; }
         if(t->data > data){
            lD->rP = t;
            lD->lP = t->lP;
            t->lP->rP = lD;
            t->lP = lD; 
            return 1;
         }    
         else {
            lD->rP = NULL;
            lD->lP = t;
            t->rP = lD;
            return 1;
         }
     }  
}