#include <stdio.h>
#include <stdlib.h>

struct drvo
{
    int i;
    struct drvo *left;
    struct drvo *right;
};

int main()
{
    struct drvo *p = NULL, *q = NULL, *r = NULL, *t = NULL;

    // 1
    p = (struct drvo *)malloc(sizeof(struct drvo));
    if (p == NULL)
        exit(1);
    p->i = 1;
    p->left = NULL;
    p->right = NULL;

    // 2
    q = (struct drvo *)malloc(sizeof(struct drvo));
    if (q == NULL)
        exit(1);
    q->i = 2;
    q->left = NULL;
    q->right = NULL;
    p->left = q;

    // 3
    r = (struct drvo *)malloc(sizeof(struct drvo));
    if (r == NULL)
        exit(1);
    r->i = 3;
    r->left = NULL;
    r->right = NULL;
    p->right = r;

    t = q;

    // 4
    q = (struct drvo *)malloc(sizeof(struct drvo));
    if (q == NULL)
        exit(1);
    q->i = 4;
    q->left = NULL;
    q->right = NULL;
    t->left = q;

    // 5
    q = (struct drvo *)malloc(sizeof(struct drvo));
    if (q == NULL)
        exit(1);
    q->i = 5;
    q->left = NULL;
    q->right = NULL;
    t->right = q;

    t = q;

    // 6
    q = (struct drvo *)malloc(sizeof(struct drvo));
    if (q == NULL)
        exit(1);
    q->i = 6;
    q->left = NULL;
    q->right = NULL;
    t->left = q;

    // 7
    q = (struct drvo *)malloc(sizeof(struct drvo));
    if (q == NULL)
        exit(1);
    q->i = 7;
    q->left = NULL;
    q->right = NULL;
    r->right = q;
}