Teacher's Dilemma || Hackerrank

#include <bits/stdc++.h>
#define endl '\n'
const int mod = 1e9 + 7;
const int MAX = 1e5 + 7;
using namespace std;

int parent[MAX];

int find(int a) {
    if(parent[a] < 0) {
        return a;
    } else {
        return parent[a] =  find(parent[a]);
    }
}

void Union(int a, int b) {
    parent[a] += parent[b];
    parent[b] = a;
}

int main() {
    int n, m, u, v, a, b;
    cin >> n >> m;

    for(int i = 0; i <= n; i++) {
        parent[i] = -1;
    }

    for(int i = 1; i <= n; i++) {
        int a, b;
        cin >> a >> b;
        a = find(a);
        b = find(b);
        if(a != b) {
            Union(a, b);
        }
    }


    long long int mul = 1;

    for (int i = 1; i <= n; i++) {
        if(parent[i] < 0) {
            mul = ((mul % mod) * (abs(parent[i]) % mod)) % mod;
        }
    }

   cout << mul << endl;

    return 0;
}