#include <bits/stdc++.h>
using namespace std;

#define rep(i, j, n) for(int i=j;i<n;++i)
#define all(i) i.begin(),i.end()
#define rall(i) i.rbegin(),i.rend()
#define INF 1e9
const int mod = 1e9 + 7;

typedef long long i64;
typedef pair<int, int> pi;

template <class T> using vt = vector<T>;
template <class T> using vvt = vector<vector<T>>;

i64 gcd(i64 n, i64 m) {return (m == 0? n : gcd(m, n % m));}
i64 lcm(i64 n, i64 m) {return (n / gcd(n, m) * m);}
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};

int n, m;
vt<int> a;
vvt<int> edge;

int num[3];
bool ok = false;

void dfs(int i, int v) {
  if(ok) return;

  num[i] = a[v];
  if(i == 2) {
    if(num[0] != num[1] && num[1] != num[2] && num[2] != num[0]) {
      ok = true;
    }
    return;
  }

  for(auto nxt : edge[v]) {
    dfs(i + 1, nxt);
  }
}

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

  cin >> n >> m;
  a.resize(n);
  rep(i, 0, n) cin >> a[i];
  edge.resize(n);
  rep(i, 0, m) {
    int u, v;
    cin >> u >> v;
    u--; v--;
    edge[u].push_back(v);
    edge[v].push_back(u);
  }

  rep(i, 0, n) dfs(0, i);

  if(ok) cout <<"YES\n";
  else cout << "NO\n";
}