/*

     暴力：也是暴力过了，无语。无向图，两端点都要加度数和点

 */

 #include <cstdio>

 #include <algorithm>

 #include <cstring>

 #include <vector>

 #include <cmath>

 using namespace std;

 typedef long long ll;

 const int MAXN = 2e2 + ;

 const int INF = 0x3f3f3f3f;

 ll a[MAXN];

 vector<int> G[MAXN];

 int degree[MAXN];

 int main(void)        //hihoCoder 1179 永恒游戏

 {

     // freopen ("C.in", "r", stdin);

     int n, m;

     while (scanf ("%d%d", &n, &m) == )

     {

         for (int i=; i<n; ++i)    scanf ("%lld", &a[i]);

         for (int i=; i<n; ++i)    G[i].clear ();

         memset (degree, , sizeof (degree));

         while (m--)

         {

             int u, v;    scanf ("%d%d", &u, &v);

             degree[u]++;    degree[v]++;

             G[u].push_back (v);    G[v].push_back (u);

         }

         bool ok = false;

         for (int i=; i<=; ++i)

         {

             ok = false;

             for (int j=; j<n; ++j)

             {

                 if (a[j] >= degree[j])

                 {

                     for (int k=; k<G[j].size (); ++k)

                     {

                         a[j]--;    a[G[j][k]]++;

                     }

                     ok = true;    break;

                 }

             }

             if (!ok)    {printf ("%d\n", i - ); break;}

         }

         if (ok)    puts ("INF");

     }

     return ;

 }