Why does this code fail?

general
,
1

This is my solution to the recent AtCoder ABC356 Problem C


#include <bits/stdc++.h>

using namespace std;
int M = 1e9 + 7;

void sort(vector<int> &a) {
    sort(a.begin(), a.end());
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    map<set<int>, bool> a;
    int n, m, K;
    int ans = 0;
    cin >> n >> m >> K;
    for (int i = 0; i < m; i++) {
        int c;
        cin >> c;
        set<int> s;
        for (int j = 0; j < c; j++) {
            int x;
            cin >> x;
            s.insert(x);
        }

        char ch;
        cin >> ch;
        a[s] = ch == 'o';
    }

    for (int b = 1; b < (1 << n); b++) {
        set<int> st;
        for (int i = 0; i < n; i++) {
            if (b & (1<<i)) st.insert(i + 1);
        }
        //if (st.size() < K) continue;

        bool can = true;
        for (const auto& i : a) {
            int ct = 0;
            for (auto e : st) {
                if (i.first.count(e)) ++ct;
            }
            if (i.second) {
                if (ct < K) can = false;
            } else {
                if (ct >= K) can = false;
            }
        }
        ans += can;
    }

    cout << ans << "\n";
}

My solution is similar in logic and code to the one suggested in official editorial, but got WA on 4 test. Please help.