#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
const ll N=1e5+3,INF=(ll)1e18;
ll n,m,k,px[N],py[N],a[N];
bool vis[N];
struct Flow
{
    ll tot=1,hd[N],ne[N],to[N],lim[N];
    void Add(int x,int y,ll z)
    {
        ne[++tot]=hd[x];hd[x]=tot;to[tot]=y;lim[tot]=z;
        ne[++tot]=hd[y];hd[y]=tot;to[tot]=x;lim[tot]=0;
    }
    ll T,dis[N],cur[N];
    ll Dfs(ll x,ll res)
    {
        if(x==T)return res;
        ll flow=0;
        for(int i=cur[x];i&&res;i=ne[i])
        {
            cur[x]=i;ll w=min(res,lim[i]),y=to[i],z;
            if(dis[x]+1==dis[y]&&w)z=Dfs(y,w),flow+=z,res-=z,lim[i]-=z,lim[i^1]+=z;
        }
        if(!flow)dis[x]=-1;
        return flow;
    }
    ll Maxflow(int s,int t)
    {
        T=t;ll flow=0;
        while(1)
        {
            queue<int>q;q.push(s);memcpy(cur,hd,sizeof(hd));
            memset(dis,-1,sizeof(dis));dis[s]=0;
            while(!q.empty())
            {
                int x=q.front();q.pop();
                for(int i=hd[x];i;i=ne[i])if(dis[to[i]]==-1&&lim[i])
                    dis[to[i]]=dis[x]+1,q.push(to[i]);
            }
            if(dis[t]==-1)return flow;
            flow+=Dfs(s,INF);
        }
    }
    bool v[N];
    void Bfs(int x)
	{
		queue<int>q;v[x]=1;q.push(x);
		while(!q.empty())
		{
			int x=q.front();q.pop();
			for(int i=hd[x];i;i=ne[i])
				if(!v[to[i]]&&lim[i])v[to[i]]=1,q.push(to[i]);
		}
	}
}G[6];
int main()
{
	cin>>n>>m>>k;ll S,T,ans=0;cin>>S>>T;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1;i<=m;i++)cin>>px[i]>>py[i];
	for(int t=1;t<=k;t++)
	{
		for(int i=1;i<=m;i++)G[t].Add(px[i]+n,py[i],INF); 
		for(int i=1;i<=n;i++)G[t].Add(i,i+n,vis[i]?INF:a[i]);
		if(G[t].Maxflow(S,T+n)>=INF){cout<<-1;return 0;}
		G[t].Bfs(S);
		for(int i=1;i<=n;i++)if(G[t].v[i]!=G[t].v[i+n])vis[i]=1;
	}
	for(int i=1;i<=n;i++)if(vis[i])ans+=a[i];
	cout<<ans;
}