#include <iostream>

#include <cstdio>

#include <cmath>

#include <algorithm>

#include <vector>

#include <iomanip>

#include <cstring>

#include <map>

#include <queue>

#include <set>

#include <cassert>

#include <stack>

#include <bitset>

#define mkp make_pair

using namespace std;

const double EPS=1e-;

typedef long long lon;

const lon SZ=,SSZ=,APB=,one=,INF=0x7FFFFFFF,mod=;

int n,m,S=,T=,dep[SZ];

int mp[SZ][SZ];

void add(int u,int v,int w)

{

    mp[u][v]=w;

}

void init()

{

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

    {

        int tmp;

        cin>>tmp;

        if(!tmp)

        {

            add(S,i,APB+);

            add(i,S,);

            add(i,T,APB);

            add(T,i,);

        }

        else

        {

            add(S,i,APB);

            add(i,S,);

            add(i,T,APB+);

            add(T,i,);

        }

    }

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

    {

        int a,b;

        cin>>a>>b;

        add(a,b,);

        add(b,a,);

    }

}

bool bfs()

{

    memset(dep,,sizeof(dep));

    dep[S]=;

    queue<int> q;

    q.push(S);

    for(;q.size();)

    {

        int fr=q.front();

        q.pop();

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

        {

            if(!dep[i]&&mp[fr][i])

            {

                dep[i]=dep[fr]+;

                q.push(i);

                if(i==T)return ;

            }

        }

    }

    return ;

}

int dinic(int x,int flow)

{

    if(x==T)return flow;

    else

    {

        int rem=flow;

        for(int i=;i<=T&&rem;++i)

        {

            if(dep[i]==dep[x]+&&mp[x][i])

            {

                int tmp=dinic(i,min(rem,mp[x][i]));

                if(!tmp)dep[i]=;

                rem-=tmp;

                mp[x][i]-=tmp,mp[i][x]+=tmp;

            }

        }

        return flow-rem;

    }

}

void work()

{

    int res=;

    for(;bfs();)res+=dinic(S,INF);

    cout<<res-n*APB<<endl;

}

void release()

{

    memset(mp,,sizeof(mp));

}

int main()

{

    std::ios::sync_with_stdio();

    //freopen("d:\\1.txt","r",stdin);

    //cout<<(1<<31)<<endl;

    int casenum;

    //cin>>casenum;

    //cout<<casenum<<endl;

    //for(int time=1;time<=casenum;++time)

    for(int time=;cin>>n>>m,n;++time)

    {

        init();

        work();

        release();

    }

    return ;

}