#include <bits/stdc++.h>
#define ll long long
#define V vector<long long>
#define VV vector<vector<long long>>
#define VVV vector<vector<vector<long long>>>
#define P pair<ll,ll>
#define rep(i,n) for(ll (i)=0;(i)<(n);++(i))
#define per(i,n) for(ll (i)=(n)-1;(i)>=0;--(i))
#define all(x) (x).begin(),(x).end()
using namespace std;

std::vector<int> Eratosthenes( const int N )
{
    std::vector<bool> is_prime( N + 1 );
    for( int i = 0; i <= N; i++ )
    {
        is_prime[ i ] = true;
    }
    std::vector<int> p;
    for( int i = 2; i <= N; i++ )
    {
        if( is_prime[ i ] )
        {
            for( int j = 2 * i; j <= N; j += i )
            {
                is_prime[ j ] = false;
            }
            p.emplace_back( i );
        }
    }
    return p;
}

long long gcd(long long a, long long b) {
    if (b == 0) return a;
    else return gcd(b, a % b);
}

int main(){
    ll n;
    cin>>n;
    V x(n);
    rep(i,n)cin>>x[i];
    vector<int> pri=Eratosthenes(50);
    ll N=pri.size();
    ll ans=1e18;
    ll tmp=1;
    for(ll bit=0;bit<(1<<N);bit++){
        ll num=1;
        rep(k,N){
            if(1<<k&bit){
                num*=pri[k];
            }
        }
        if(num==1)continue;
        bool ok=true;
        rep(i,n){
            if(gcd(num,x[i])==1){
                ok=false;
                break;
            }
        }
        if(ok)ans=min(ans,num);
    }
    cout<<ans<<endl;
}

#include <bits/stdc++.h>
using namespace std;
// type alias
typedef long long LL;
typedef pair<int,int> II;
typedef tuple<int,int,int> III;
typedef vector<int> VI;
typedef vector<string> VS;
typedef unordered_map<int,int> MAPII;
typedef unordered_set<int> SETI;
template<class T> using VV=vector<vector<T>>;
// minmax
template<class T> inline T SMIN(T& a, const T b) { return a=(a>b)?b:a; }
template<class T> inline T SMAX(T& a, const T b) { return a=(a<b)?b:a; }
// repetition
#define FORE(i,a,b) for(int i=(a);i<=(b);++i)
#define REPE(i,n)  for(int i=0;i<=(n);++i)
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  for(int i=0;i<(n);++i)
#define FORR(x,arr) for(auto& x:arr)
#define SZ(a) int((a).size())
// collection
#define ALL(c) (c).begin(),(c).end()
// DP
#define MINUS(dp) memset(dp, -1, sizeof(dp))
#define ZERO(dp) memset(dp, 0, sizeof(dp))
// stdout
#define println(args...) fprintf(stdout, ##args),putchar('\n');
// debug cerr
template<class Iter> void __kumaerrc(Iter begin, Iter end) { for(; begin!=end; ++begin) { cerr<<*begin<<','; } cerr<<endl; }
void __kumaerr(istream_iterator<string> it) { (void)it; cerr<<endl; }
template<typename T, typename... Args> void __kumaerr(istream_iterator<string> it, T a, Args... args) { cerr<<*it<<"="<<a<<", ",__kumaerr(++it, args...); }
template<typename S, typename T> std::ostream& operator<<(std::ostream& _os, const std::pair<S,T>& _p) { return _os<<"{"<<_p.first<<','<<_p.second<<"}"; }
#define __KUMATRACE__ true
#ifdef __KUMATRACE__
#define dump(args...) { string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); __kumaerr(_it, args); }
#define dumpc(ar) { cerr<<#ar<<": "; FORR(x,(ar)) { cerr << x << ','; } cerr << endl; }
#define dumpC(beg,end) { cerr<<"~"<<#end<<": "; __kumaerrc(beg,end); }
#else
#define dump(args...)
#define dumpc(ar)
#define dumpC(beg,end)
#endif

// $ cp-batch Peddler | diff Peddler.out -
// $ g++ -std=c++14 -Wall -O2 -D_GLIBCXX_DEBUG -fsanitize=address Peddler.cpp && ./a.out

/*

 1/17/2021

 11:07-

 */

const int MAX_N=1e6+1;
LL A[MAX_N];
int N,M;

const LL Inf=1e18;
LL dp[MAX_N][3];
VI G[MAX_N];
void solve() {
  REP(i,N)REP(j,3) dp[i][j]=-Inf;
  REP(i,N) dp[i][0]=0;
  REP(u,N)REP(j,3) {
    FORR(v,G[u]) {
      SMAX(dp[v][j],dp[u][j]);
      if(j==0) SMAX(dp[v][1],dp[u][0]-A[u]);
      if(j==1) SMAX(dp[v][2],dp[u][1]+A[u]);
      //dump(u,j,v,dp[v][j+1]);
    }
  }
  REP(u,N) SMAX(dp[u][2],dp[u][1]+A[u]);

  LL res=-Inf;
  REP(u,N) SMAX(res,dp[u][2]);
  cout<<res<<endl;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout<<setprecision(12)<<fixed;

  cin>>N>>M;
  REP(i,N) cin>>A[i];
  REP(_,M) {
    int u,v; cin>>u>>v;
    --u,--v;
    G[u].push_back(v);
  }
  solve();

  return 0;
}
