#include <cstdio>  
#include <cstring>  
#include <cstdlib>  
#include <string>  
#include <iostream>  
#include <algorithm>  
#include <sstream>  
#include <cmath>  
using namespace std;  
#include <queue>  
#include <stack>  
#include <vector>  
#include <deque>  
#include <map>  
#define cler(arr, val)    memset(arr, val, sizeof(arr))  
typedef long long  LL;  
const int MAXN = 543;  
const int MAXM = 260110;  
const int INF = 0x3f3f3f3f;  
const int mod = 1000000007;  
struct Edge  
{  
    int to,next,cap,flow;  
}edge[MAXM];
int tol;  
int head[MAXN];  
int gap[MAXN],dep[MAXN],pre[MAXN],cur[MAXN];  
void init()  
{  
    tol = 0;  
    memset(head,-1,sizeof (head));  
}  
void addedge (int u,int v,int w,int rw=0)  
{  
    edge[tol].to = v;edge[tol].cap = w;edge[tol].next = head[u];  
    edge[tol].flow = 0;head[u] = tol++;  
    edge[tol].to = u;edge[tol].cap = rw;edge[tol]. next = head[v];  
    edge[tol].flow = 0;head[v]=tol++;  
}    
int sap(int start,int end, int N)  
{  
    memset(gap,0,sizeof(gap));  
    memset(dep,0,sizeof(dep));  
    memcpy(cur,head,sizeof(head));  
    int u = start;  
    pre[u] = -1;  
    gap[0] = N;  
    int ans = 0;  
    int i;  
    while(dep[start] < N)  
    {  
        if(u == end)  
        {  
            int Min = INF;  
            for( i = pre[u];i != -1; i = pre[edge[i^1]. to])  
            {  
                if(Min > edge[i].cap - edge[i]. flow)  
                    Min = edge[i].cap - edge[i].flow;  
            }  
            for( i = pre[u];i != -1; i = pre[edge[i^1]. to])  
            {  
                edge[i].flow += Min;  
                edge[i^1].flow -= Min;  
            }  
            u = start;  
            ans += Min;  
            continue;  
        }  
        bool flag =  false;  
        int v;  
        for( i = cur[u]; i != -1;i = edge[i].next)  
        {  
            v = edge[i]. to;  
            if(edge[i].cap - edge[i].flow && dep[v]+1 == dep[u])  
            {  
                flag =  true;  
                cur[u] = pre[v] = i;  
                break;  
            }  
        }  
        if(flag)  
        {  
            u = v;  
            continue;  
        }  
        int Min = N;  
        for( i = head[u]; i !=  -1;i = edge[i]. next)  
        {  
            if(edge[i].cap - edge[i].flow && dep[edge[i].to] < Min)  
            {  
                Min = dep[edge[i].to];  
                cur[u] = i;  
            }  
        }  
        gap[dep[u]]--;  
        if(!gap[dep[u]]) return ans;  
        dep[u] = Min+1;  
        gap[dep[u]]++;  
        if(u != start) u = edge[pre[u]^1].to;  
    }  
    return ans;  
}  
int n,m,s,e;  
void build()  
{  
    init();  
    s=n+1,e=n+2;  
    int u,v,w;  
    for(int i=1;i<=n;i++)  
    {  
        scanf("%d",&w);  
        if(w==0)  
            addedge(s,i,1);  
        else  
            addedge(i,e,1);  
    }  
    for(int i=1;i<=m;i++)  
    {  
        scanf("%d%d",&u,&v);  
        addedge(u,v,1);  
        addedge(v,u,1);  
    }  
}  
int main()  
{  
    while(scanf("%d%d",&n,&m),n+m)  
    {  
        build();  
        printf("%d\n",sap(s,e,n+2));  
    }  
    return 0;  
}