n, m = map(int, input().split())
nodes = sorted([input() for _ in range(n)])
edges = {tuple(input().split()) for _ in range(m)}
n = len(nodes)
total_combinations = 2**n
team = []
for i in range(total_combinations):
combination = []
for j in range(n):
if (i >> j) & 1:
combination.append(nodes[j])
conflict = False
for a,b in edges:
if a in combination and b in combination:
conflict = True
break
if not conflict and len(team) < len(combination):
team = combination
print(len(team))
for i in team:
print(i)#include <iostream>
#include <climits>
#include <cmath>
#include <algorithm>
#include <vector>
#include <map>
#include <stack>
#include <set>
#include <queue>
#include <unordered_set>
#include <unordered_map>
#define show(C) for (auto J: C) cout << J << " "; cout << endl;
#define ll long long
#define F(I, S, E) for(ll I = S; I < E; I++)
#define input(a,n) for(ll I = 0; I < n; I++){cin>>a[I];}
#define PYES cout << "YES\n"
#define PNO cout << "NO\n"
#define vi vector<ll>
#define pi pair<ll,ll>
#define f first
#define s second
#define pb push_back
using namespace std;
void solve()
{
int n,m;cin>>n>>m;
vector<string> person(n);
vector<int> inc(n,0);
map<string,int> mpp;
for(int i=0;i<n;i++){cin>>person[i];mpp[person[i]]=i;}
vector<vector<int> > adj(n);
for(int i=0;i<m;i++)
{
string a,b;
cin>>a>>b;
adj[mpp[a]].push_back(mpp[b]);
adj[mpp[b]].push_back(mpp[a]);
}
int len=0;
for(int mask=0;mask<(1<<n);mask++)
{
// each of 2 to power n subset
bool can=true;
set<int> enemy;
vector<int> temp(n,0);
int cnt=0;
for(int i=0;i<n;i++)
{
if(mask & (1<<i))
{
temp[i]=1;cnt++;
if(enemy.find(i)!=enemy.end()){can=false;break;}
else
{
for(auto it:adj[i])enemy.insert(it);
}
}
}
if(can)
{
if(cnt>len)
{
len=cnt;
for(int i=0;i<n;i++)inc[i]=temp[i];
}
}
}
cout<<len<<endl;
set<string> res;
for(int i=0;i<n;i++)
{
if(inc[i])res.insert(person[i]);
}
for(auto it:res)cout<<it<<endl;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
// cin>>t;
while(t--)
{
solve();
}
return 0;
}1459B - Move and Turn | 1006F - Xor-Paths |
706C - Hard problem | 304C - Lucky Permutation Triple |
1301C - Ayoub's function | 38E - Let's Go Rolling |
171G - Mysterious numbers - 2 | 1183C - Computer Game |
400C - Inna and Huge Candy Matrix | 417A - Elimination |
222A - Shooshuns and Sequence | 1736A - Make A Equal to B |
1736B - Playing with GCD | 887C - Solution for Cube |
1737C - Ela and Crickets | 1741C - Minimize the Thickness |
1741A - Compare T-Shirt Sizes | 1741D - Masha and a Beautiful Tree |
109B - Lucky Probability | 1741B - Funny Permutation |
1741E - Sending a Sequence Over the Network | 344B - Simple Molecules |
370A - Rook Bishop and King | 546E - Soldier and Traveling |
1741G - Kirill and Company | 1200B - Block Adventure |
1088B - Ehab and subtraction | 1270B - Interesting Subarray |
478C - Table Decorations | 1304C - Air Conditioner |