#include "bits/stdc++.h"

#define REP(i, n, N) for(ll i=(n); i<(N); i++)
#define RREP(i, n, N) for(ll i=(N-1); i>=n; i--)
#define SPACEREP(lst,itr) for(auto itr=lst.begin(); itr!=lst.end();++itr){cout<<*itr<<(++itr!=anslist.end()?" ":"\n");itr--;}
#define CK(n, a, b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define MCP(a, b) memcpy(b,a,sizeof(b))
#define p(s) cout<<(s)<<endl
#define p2(a, b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const ll mod = 1e9 + 7;
const ll inf = 1e18;

int main(){
    int N,M;
    cin >> N >> M;
    vector<vector<pair<int,int>>> edge(N+1);
    vector<int> value(N+1);

    int u,v;
    REP(i,1,N+1){
        cin >> value[i];
    }
    REP(i,1,M+1){
        cin >> u >> v;
        if(value[u]-value[v]==0)continue;
        edge[u].push_back(make_pair(v,value[u]-value[v]));
        edge[v].push_back(make_pair(u,value[v]-value[u]));
    }

    bool flag=false;
    REP(i,1,N+1){
        for(auto x : edge[i]){
            for(auto y : edge[i]){
                if(x.first==y.first)continue;
                if(x.second==y.second)continue;
                if(x.second<0 && y.second>0)continue;
                if(x.second>0 && y.second<0)continue;
                flag=true;
            }
        }
    }

    cout << (flag ? "YES" : "NO") << endl;
}