/**************************************************************

     Problem: 2768

     User: Tunix

     Language: C++

     Result: Accepted

     Time:32 ms

     Memory:4408 kb

 ****************************************************************/

 //BZOJ 2768

 #include<vector>

 #include<cstdio>

 #include<cstring>

 #include<cstdlib>

 #include<iostream>

 #include<algorithm>

 #define rep(i,n) for(int i=0;i<n;++i)

 #define F(i,j,n) for(int i=j;i<=n;++i)

 #define D(i,j,n) for(int i=j;i>=n;--i)

 #define pb push_back

 using namespace std;

 inline int getint(){

     int v=,sign=; char ch=getchar();

     while(ch<''||ch>''){ if (ch=='-') sign=-; ch=getchar();}

     while(ch>=''&&ch<=''){ v=v*+ch-''; ch=getchar();}

     return v*sign;

 }

 const int N=,M=,INF=~0u>>;

 typedef long long LL;

 /******************tamplate*********************/

 int n,m;

 struct edge{

     int from,to,v;

 };

 inline int pack(int i,int j){return (i-)*m+j;}

 struct Net{

     edge E[M];

     int head[N],next[M],cnt;

     void add(int x,int y,int v){

         E[++cnt]=(edge){x,y,v};

         next[cnt]=head[x]; head[x]=cnt;

         E[++cnt]=(edge){y,x,};

         next[cnt]=head[y]; head[y]=cnt;

     }

     int s,t,cur[N],d[N],Q[N];

     void init(){

         n=getint();m=getint();

         cnt=;

         s=; t=n+;

         F(i,,n)

             if (getint()) add(s,i,);

             else add(i,t,);

         int x,y;

         F(i,,m){

             x=getint(); y=getint();

             add(x,y,);

             add(y,x,);

         }

     }

     bool mklevel(){

         memset(d,-,sizeof d);

         d[s]=;

         int l=,r=-;

         Q[++r]=s;

         while(l<=r){

             int x=Q[l++];

             for(int i=head[x];i;i=next[i])

                 if (d[E[i].to]==- && E[i].v){

                     d[E[i].to]=d[x]+;

                     Q[++r]=E[i].to;

                 }

         }

         return d[t]!=-;

     }

     int dfs(int x,int a){

         if (x==t||a==) return a;

         int flow=;

         for(int &i=cur[x];i && flow<a;i=next[i])

             if (d[E[i].to]==d[x]+ && E[i].v){

                 int f=dfs(E[i].to,min(a-flow,E[i].v));

                 E[i].v-=f;

                 E[i^].v+=f;

                 flow+=f;

             }

         if (!flow) d[x]=-;

         return flow;

     }

     int Dinic(){

         int flow=;

         while(mklevel()){

             F(i,s,t) cur[i]=head[i];

             flow+=dfs(s,INF);

         }

         return flow;

     }

 }G1;

 int main(){

 #ifndef ONLINE_JUDGE

     freopen("2768.in","r",stdin);

     freopen("2768.out","w",stdout);

 #endif

     G1.init();

     printf("%d\n",G1.Dinic());

     return ;

 }