n,m=map(int,input().split())
a=list(map(int,input().split()))
e=[[] for i in range(n)]
for i in range(n-1):
  u,v=map(int,input().split())
  u-=1
  v-=1
  e[u]+=[v]
  e[v]+=[u]
v=[0]*n
p=[0]*n
u1=[0]*n
c=[[0]*(len(e[i])+1) for i in range(n)]
q=[0]
while len(q)>0:
  s=q[-1]
  if v[s]==0:
    v[s]=1
    for t in e[s]:
      if v[t]==0:
        p[t]=s
        q+=[t]
  else:
    for t in e[s]:
      if v[t]==0 and u1[t]<=len(e[s]):
        c[s][u1[t]]+=1
    for i in range(len(e[s])+1):
      if c[s][i]==0:
        u1[s]=i
        break
    v[s]=0
    q.pop()
u2=[0]*n
q=[0]
while len(q)>0:
  s=q[-1]
  if v[s]==0:
    v[s]=1
    if s!=0:
      if u2[s]<=len(e[s]):
        c[s][u2[s]]+=1
    for i in range(len(e[s])+1):
      if c[s][i]==0:
        g=i
        break
    for t in e[s]:
      if v[t]==0:
        if u1[t]<g and c[s][u1[t]]-1==0:
          u2[t]=u1[t]
        else:
          u2[t]=g
        q+=[t]
  else:
    v[s]=0
    q.pop()
f=[0]*n
for y in a:
  f[y-1]^=1
g=0
for s in range(n):
  if f[s]%2:
    for i in range(len(e[s])+1):
      if c[s][i]==0:
        g^=i
        break
if g==0:
  print(-1,-1)
  exit()
for s in range(n):
  if f[s]>0:
    for i in range(len(e[s])+1):
      if c[s][i]==0:
        g^=i
        for t in e[s]:
          if p[s]!=t:
            if g^u1[t]==0:
              print(a.index(s+1)+1,t+1)
              exit()
          else:
            if g^u2[s]==0:
              print(a.index(s+1)+1,t+1)
              exit()