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

typedef struct TreeNode {
    int d;
    struct TreeNode *l, *r;
} T;

T *c(int d) {
    T *n = malloc(sizeof(T));
    n->d = d;
    n->l = n->r = NULL;
    return n;
}

T *i(T *r, int d) {
    if (!r) return c(d);
    if (d < r->d) r->l = i(r->l, d);
    else if (d > r->d) r->r = i(r->r, d);
    return r;
}

T *f(T *r) {
    while (r->l) r = r->l;
    return r;
}

T *d(T *r, int k) {
    if (!r) return NULL;
    if (k < r->d) r->l = d(r->l, k);
    else if (k > r->d) r->r = d(r->r, k);
    else {
        if (!r->l) {
            T *t = r->r;
            free(r);
            return t;
        } else if (!r->r) {
            T *t = r->l;
            free(r);
            return t;
        }
        T *t = f(r->r);
        r->d = t->d;
        r->r = d(r->r, t->d);
    }
    return r;
}

void t(T *r) {
    if (r) {
        t(r->l);
        printf("%d ", r->d);
        t(r->r);
    }
}

int s(T *r, int k, int *p) {
    if (!r) return 0;
    int l = s(r->l, k, p);
    if (l) return l;
    if (++*p == k) return *p;
    return s(r->r, k, p);
}

int main() {
    T *r = NULL;
    int c, v;
    while (1) {
        printf("\n1. Insert\n2. Delete\n3. Search\n4. Display\n5. Exit\n");
        scanf("%d", &c);
        if (c == 1) {
            scanf("%d", &v);
            r = i(r, v);
        } else if (c == 2) {
            scanf("%d", &v);
            r = d(r, v);
        } else if (c == 3) {
            scanf("%d", &v);
            int p = 0, f = s(r, v, &p);
            printf(f ? "Found at %d\n" : "Not found\n", f);
        } else if (c == 4) {
            t(r);
            printf("\n");
        } else if (c == 5) {
            break;
        } else {
            printf("Invalid\n");
        }
    }
    free(r);
    return 0;
}