diff --git a/I.py b/I.py
new file mode 100644
index 0000000..c5f24cf
--- /dev/null
+++ b/I.py
@@ -0,0 +1,42 @@
+from __future__ import print_function
+import heapq, sys
+
+def dijkstra(G, s):
+  V, E = G; d = {}; S = set(); q = []
+  for u in V: d.setdefault(u, None)
+  for u in s:
+    d[u] = 0; heapq.heappush(q, (0,u))
+  while q:
+    n, u = heapq.heappop(q)
+    if u in S: continue
+    S.add(u)
+    for v in E[u]:
+      if d[v] is None or d[v] > d[u] + 1:
+        d[v] = d[u] + 1; heapq.heappush(q, (d[v],v))
+  return d
+
+def transpose(G):
+  V, E = G; ET = {}
+  for u in V: ET[u] = []
+  for u, vs in E.iteritems():
+    for v in vs: ET[v].append(u)
+  return V, ET
+
+n, m, k = map(int, sys.stdin.readline().split())
+iron    = [ int(x)-1 for x in sys.stdin.readline().split() ]
+coal    = [ int(x)-1 for x in sys.stdin.readline().split() ]
+V, E    = range(n), {}
+for i, line in enumerate(sys.stdin):
+  E[i] = [ int(x)-1 for x in line.split()[1:] ]
+G       = V, E
+GT      = transpose(G)
+ds      = dijkstra(G, [0])
+di      = dijkstra(GT, iron)
+dc      = dijkstra(GT, coal)
+try:
+  m = min( ds[i]+di[i]+dc[i] for i in xrange(n)
+           if None not in (ds[i],di[i],dc[i]) )
+  print(m)
+except ValueError as e:
+  if "empty" not in e.args[0]: raise
+  print("impossible")