n,m = map(int,input().split())
h = list(map(int,input().split()))
graph = [[] for i in range(n+1)]
for i in range(m):
  a,b = map(int,input().split())
  graph[a-1].append(b-1)
  graph[b-1].append(a-1)

for i in range(n):
  graph[i].sort()


import heapq
#ダイクストラ法
INF = 10**15
dist = [[INF,INF] for i in range(n*1)]
que = [(0,0,0), (0,1,0)]
dist[0][0] = 0
dist[0][1] = 0
while que:
  c,ud,crr = heapq.heappop(que)
  if c > dist[crr][ud]: continue
  for nxt in graph[crr]:
    if crr > nxt: break
    if ud == 0:
      if h[nxt] < h[crr]: 
        if dist[crr][0] < dist[nxt][1]:
          dist[nxt][1] = dist[crr][0] 
          heapq.heappush(que,(dist[nxt][1],1,nxt))
      else:
        if dist[crr][0] + (h[crr]-h[nxt]) < dist[nxt][1]:
          dist[nxt][1] = dist[crr][0] +  (h[crr]-h[nxt]) 
          heapq.heappush(que,(dist[nxt][1],1,nxt))
    else:
      if h[nxt] > h[crr]: continue
      if dist[crr][1] < dist[nxt][0]:
        dist[nxt][0] = dist[crr][1] 
        heapq.heappush(que,(dist[nxt][0],0,nxt))
ans = min(dist[n-1])
print(-1) if ans == INF else print(-ans)
dist = [[INF,INF] for i in range(n*1)]
que = [(0,0,n-1), (0,1,n-1)]
dist[n-1][0] = 0
dist[n-1][1] = 0
while que:
  c,ud,crr = heapq.heappop(que)
  if c > dist[crr][ud]: continue
  for nxt in graph[crr]:
    if crr < nxt: break
    if ud == 0:
      if h[nxt] < h[crr]: 
        if dist[crr][0] < dist[nxt][1]:
          dist[nxt][1] = dist[crr][0] 
          heapq.heappush(que,(dist[nxt][1],1,nxt))
      else:
        if dist[crr][0] + (h[crr]-h[nxt]) < dist[nxt][1]:
          dist[nxt][1] = dist[crr][0] +  (h[crr]-h[nxt]) 
          heapq.heappush(que,(dist[nxt][1],1,nxt))
    else:
      if h[nxt] > h[crr]: continue
      if dist[crr][1] < dist[nxt][0]:
        dist[nxt][0] = dist[crr][1] 
        heapq.heappush(que,(dist[nxt][0],0,nxt))
ans = min(dist[0])
print(-1) if ans == INF else print(-ans)