#include<cstdio>
#include<queue>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
const int N=2e3+5;
const int M=1e6+5;
const ll inf=1e18;
struct edge
{
	int next,to;
	ll fl;
}e[M];
bool vis[N];
int n,m,k,s,t,cnt=1,in[N],cur[N],dep[N];
ll read()
{
	ll res,f=1;
	char ch;
	while((ch=getchar())<'0'||ch>'9')
	if(ch=='-')
	f=-1;
	res=ch^48;
	while((ch=getchar())>='0'&&ch<='9')
	res=(res<<1)+(res<<3)+(ch^48);
	return res*f;
}
void add(int x,int y,ll fl)
{
	e[++cnt].next=in[x];
	e[cnt].to=y;
	e[cnt].fl=fl;
	in[x]=cnt;
	e[++cnt].next=in[y];
	e[cnt].to=x;
	e[cnt].fl=0;
	in[y]=cnt;
}
bool bfs()
{
	int u,i,d;
	queue<int> q;
	memcpy(cur,in,sizeof(in));
	memset(dep,0x3f3f3f3f,sizeof(dep));
	q.push(s);dep[s]=0;
	while(q.size())
	{
		u=q.front();q.pop();vis[u]=0;
		for(i=in[u];i;i=e[i].next)
		{
			d=e[i].to;
			if(dep[d]>dep[u]+1&&e[i].fl)
			{
				dep[d]=dep[u]+1;
				if(!vis[d])
				{
					q.push(d);
					vis[d]=1;
				}
			}
		}
	}
	return dep[t]!=0x3f3f3f3f;
}
ll dfs(int u,ll low)
{
	if(u==t||!low)
	return low;
	int i,d;
	ll rlow,used=0;
	for(i=cur[u];i;i=e[i].next)
	{
		cur[u]=i;d=e[i].to;
		if(dep[d]==dep[u]+1&&e[i].fl)
			if((rlow=dfs(d,min(low-used,e[i].fl))))
			{
				e[i].fl-=rlow;
				e[i^1].fl+=rlow;
				used+=rlow;
				if(used==low)
				break;
			}
	}
	return used;
}
ll dinic()
{
	ll ans=0;
	while(bfs())
	ans+=dfs(s,inf<<1);
	return ans;
}
int main()
{
	int i,j,y,hp;
	ll x;
	n=read();m=read();k=read();s=read();t=read();hp=2*n;
	for(i=1;i<=n;i++)
	{
		x=read();
		for(j=0;j<=k-1;j++)
		{
			add(j*hp+i,j*hp+n+i,x);
			if(j)
			add((j-1)*hp+i,j*hp+n+i,inf);//weak restriction
			if(j>1)
			add(i,j*hp+n+i,inf);//strong restriction
		}
	}
	for(i=1;i<=m;i++)
	{
		x=read();y=read();
		for(j=0;j<=k-1;j++)
		add(j*hp+n+x,j*hp+y,inf);
	}
	t+=(k-1)*hp+n;
	x=dinic();
	if(x<inf)
	printf("%lld",x);
	else
	printf("-1");
	return 0;
}