import sys
input = sys.stdin.readline

from heapq import heappop,heappush

N,M,K=map(int,input().split())

C=list(map(int,input().split()))


E=[[] for i in range(N)]

for i in range(M):
    x,y=map(int,input().split())
    x-=1
    y-=1
    E[x].append((y,C[i]))
    E[y].append((x,C[i]))

DP=[[1<<63]*N for i in range(K+1)]

DP[0][0]=0
Q=[(0,0,0)]

while Q:
    time,town,coupon=heappop(Q)

    if DP[coupon][town]!=time:
        continue

    for to,dis in E[town]:
        if DP[coupon][to]>time+dis:
            DP[coupon][to]=time+dis
            heappush(Q,(DP[coupon][to],to,coupon))
        if coupon+1<=K:
            if DP[coupon+1][to]>time:
                DP[coupon+1][to]=time
                heappush(Q,(DP[coupon+1][to],to,coupon+1))

ANS=1<<63
for i in range(K+1):
    ANS=min(ANS,DP[i][N-1])


if ANS>1<<62:
    print(-1)
else:
    print(ANS)