Bill of materials

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


typedef struct NOD{
    char nume[30];
    struct NOD *next;
}NOD;

NOD *creare_nod(char *s){
    NOD *nod_nou = malloc(sizeof(NOD));
    strcpy(nod_nou->nume, s);
    nod_nou -> next = NULL;
    return nod_nou;
}

NOD *adauga_nod(NOD *head, char *s){
    NOD *nr_nou = creare_nod(s), *nod = head;

    if(head == NULL)
        return nr_nou;

    while(nod->next) nod = nod-> next;
    nod -> next = nr_nou;

    return head;
}

void afisare_lista(NOD *head){
    NOD *nod = head;

    for(; nod; nod = nod->next)
        printf("%s\n", nod->nume);
}

int intersect(NOD *head1, NOD *head2){
    int nr = 0;
    for(NOD *nod1 = head1; nod1; nod1 = nod1 -> next)
        for(NOD *nod2 = head2; nod2; nod2 = nod2 -> next)
            if(strcmp(nod1->nume, nod2->nume) == 0){
                nr++;
                break;
            }
    return nr;
}

int main() {
    int n;
    char s[30];
    NOD *lista_cumparaturi = NULL, *lista_furnizor = NULL;

    scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        scanf("%s", s);
        lista_cumparaturi = adauga_nod(lista_cumparaturi, s);
    }

    while (scanf("%s", s) != EOF) {
        lista_furnizor = adauga_nod(lista_furnizor, s);
    }

    int nr_produse = intersect(lista_cumparaturi, lista_furnizor);
    printf("%d\n", nr_produse);
    return 0;
}