from collections import deque,defaultdict
N,M,K=map(int,input().split())
C=list(map(int,input().split()))
G=[[] for _ in range(N)]
D=defaultdict(int)
for i in range(M):
    u,v=map(int,input().split())
    u-=1;v-=1
    G[u].append(v)
    G[v].append(u)
    if u>v:u,v=v,u
    D[(u,v)]=C[i]
Q=deque([((0,),(0,))])
cand=[]
while Q:
    route,cost=Q.popleft()
    now=route[-1]
    if now==N-1:
        cand.append(sorted(cost))
        continue
    for nxt in G[now]:
        if nxt in route:continue
        if now>nxt:Q.append((route+(nxt,),cost+(D[(nxt,now)],)))
        else:Q.append((route+(nxt,),cost+(D[(now,nxt)],)))
if len(cand)==0:exit(print(-1))
ans=1<<60
for cost in cand:
    ans=min(ans,sum(cost[:max(1,len(cost)-K)]))
print(ans)