Сильное и независимое

#include <iostream>
using namespace std;

const int N = 1 << 25;

long long ns_for_v[50];
int dp1[N];
int first_bit[N];

void count_dp1(int L, int R) {
    for (int i = 0; i < (R - L); i++) {
        first_bit[1 << i] = i;
    }
    for (int i = 1; i < (1 << (R - L)); i++) {
        auto vi = i ^ (i & (i - 1));
        int v = first_bit[vi] + L;
        dp1[i] = max(dp1[i ^ vi], 1 + dp1[(i ^ vi) & (~ns_for_v[v])]);
    }
}

int V, S;

void req(int cnt, long long dp2, int M) {
    if (M == V) {
        int ans = cnt + dp1[~dp2 & ((1 << (V / 2)) - 1)];
        if (ans >= S) {
            cout << "YES\n";
            exit(0);
        }
        return;
    }
    req(cnt, dp2, M + 1);
    if ((dp2 >> M) & 1) {
        return;
    } else {
        req(cnt + 1, dp2 | ns_for_v[M], M + 1);
    }
}

int main() {
    cin >> V >> S;
    int E;
    cin >> E;
    for (int i = 0; i < E; ++i) {
        int a, b;
        cin >> a >> b;
        a--, b--;
        ns_for_v[a] |= 1LL << b;
        ns_for_v[b] |= 1LL << a;
    }
    count_dp1(0, V / 2);
    req(0, 0, V / 2);
    cout << "NO\n";
    return 0;
}