#include <stdio.h> #include <stdlib.h> typedef struct tnode { int x; struct tnode* lchild; struct tnode* rchild; } node, *pnode; void creat_find(int n) { pnode r; pnode root = malloc(sizeof(node)); r = root; scanf("%d", &root->x); root->lchild = NULL; root->rchild = NULL; printf("-1\n"); while (n > 1) { pnode a = malloc(sizeof(node)); scanf("%d", &a->x); a->lchild = NULL; a->rchild = NULL; while (1) { if (a->x > r->x) { if (r->rchild == NULL) { printf("%d\n", r->x); r->rchild = a; r = root; break; } else r = r->rchild; } else { if (r->lchild == NULL) { printf("%d\n", r->x); r->lchild = a; r = root; break; } else r = r->lchild; } } n--; } } int main() { int n; scanf("%d", &n); creat_find(n); return 0; }