#include <iostream>

using namespace std;
const int NRL = 26;
const int MAX = 100000;
const int MAXL = 20;
char v[MAXL];
int siz;
struct node {
    int nextp[NRL];
    int fr, sp;//in fr tin cate cuvinte se termina acolo, in sp tin cate cuvinte au acel prefix
} trie[MAX];

int main()
{
    FILE *fin, *fout;
    int n, i, poz;
    char ch, op;
    fin = fopen("trie.in", "r");
    op = fgetc(fin);
    siz = 1;//1 este radacina
    fout = fopen("trie.out", "w");
    while (isdigit(op)) {
        fscanf(fin, " ");
        op -= '0';
        ch = fgetc(fin);
        n = 0;
        while (isalpha(ch)) {
            v[n] = ch - 'a';
            ch = fgetc(fin);
            n++;
        }
        poz = 1;
        if (op == 0) {
            for (i = 0; i < n; i++) {
                trie[poz].sp++;
                if (trie[poz].nextp[v[i]] == 0) {
                    siz++;
                    trie[poz].nextp[v[i]] = siz;
                }
                poz = trie[poz].nextp[v[i]];
            }
            trie[poz].fr++;
            trie[poz].sp++;
        } else if (op == 1) {
            //sigur exista tot cuvantul
            for (i = 0; i < n; i++) {
                trie[poz].sp--;
                poz = trie[poz].nextp[v[i]];
            }
            trie[poz].sp--;
            trie[poz].fr--;
        } else if (op == 2) {
            for (i = 0; i < n; i++) {
                poz = trie[poz].nextp[v[i]];
            }
            fprintf(fout, "%d\n", trie[poz].fr);
        } else {
            if (trie[1].sp == 0) {
                fprintf(fout, "0\n");
            } else {
                i = 0;
                while (i < n && trie[trie[poz].nextp[v[i]]].sp > 0) {
                    poz = trie[poz].nextp[v[i]];
                    i++;
                }
                fprintf(fout, "%d\n", i);
            }
        }
        op = fgetc(fin);
    }
    fclose(fin);
    fclose(fout);
    return 0;
}