from collections import deque import sys readline=sys.stdin.readline class Graph: def __init__(self,V,edges=False,graph=False,directed=False,weighted=False,inf=float("inf")): self.V=V self.directed=directed self.weighted=weighted self.inf=inf if not graph: self.edges=edges self.graph=[[] for i in range(self.V)] if weighted: for i,j,d in self.edges: self.graph[i].append((j,d)) if not self.directed: self.graph[j].append((i,d)) else: for i,j in self.edges: self.graph[i].append(j) if not self.directed: self.graph[j].append(i) else: self.graph=graph self.edges=[] for i in range(self.V): if self.weighted: for j,d in self.graph[i]: if self.directed or not self.directed and i<=j: self.edges.append((i,j,d)) else: for j in self.graph[i]: if self.directed or not self.directed and i<=j: self.edges.append((i,j)) def SCC(self): reverse_graph=[[] for i in range(self.V)] for tpl in self.edges: u,v=tpl[:2] if self.weighted else tpl reverse_graph[v].append(u) postorder=self.MIV_DFS(postorder=True) scc_points=[] seen=[False]*self.V for s in postorder[::-1]: if seen[s]: continue queue=deque([s]) seen[s]=True lst=[] while queue: x=queue.popleft() lst.append(x) for y in reverse_graph[x]: if not seen[y]: seen[y]=True queue.append(y) scc_points.append(lst) l=len(scc_points) idx=[None]*self.V for i in range(l): for x in scc_points[i]: idx[x]=i scc_edges=set() for tpl in self.edges: u,v=tpl[:2] if self.weighted else tpl if idx[u]!=idx[v]: scc_edges.add((idx[u],idx[v])) scc_edges=list(scc_edges) return scc_points,scc_edges def MIV_DFS(self,initial_vertices=False,bipartite_graph=False,cycle_detection=False,directed_acyclic=False,euler_tour=False,linked_components=False,lowlink=False,parents=False,postorder=False,preorder=False,subtree_size=False,topological_sort=False,unweighted_dist=False,weighted_dist=False): if initial_vertices==False: initial_vertices=[s for s in range(self.V)] seen=[False]*self.V finished=[False]*self.V if bipartite_graph: bg=[None]*self.V cnt=-1 if directed_acyclic or cycle_detection or topological_sort: dag=True if euler_tour: et=[] if linked_components: lc=[] if lowlink: order=[None]*self.V ll=[None]*self.V idx=0 if parents or cycle_detection or lowlink or subtree_size: ps=[None]*self.V if postorder or topological_sort: post=[] if preorder: pre=[] if subtree_size: ss=[1]*self.V if unweighted_dist: uwd=[self.inf]*self.V if weighted_dist: wd=[self.inf]*self.V for s in initial_vertices: if seen[s]: continue if bipartite_graph: cnt+=1 bg[s]=(cnt,0) if linked_components: lc.append([]) if unweighted_dist: uwd[s]=0 if weighted_dist: wd[s]=0 stack=[(s,0)] if self.weighted else [s] while stack: if self.weighted: x,d=stack.pop() else: x=stack.pop() if not seen[x]: seen[x]=True stack.append((x,d) if self.weighted else x) if euler_tour: et.append(x) if linked_components: lc[-1].append(x) if lowlink: order[x]=idx ll[x]=idx idx+=1 if preorder: pre.append(x) for y in self.graph[x]: if self.weighted: y,d=y if not seen[y]: stack.append((y,d) if self.weighted else y) if bipartite_graph: bg[y]=(cnt,bg[x][1]^1) if parents or cycle_detection or lowlink or subtree_size: ps[y]=x if unweighted_dist or bipartite_graph: uwd[y]=uwd[x]+1 if weighted_dist: wd[y]=wd[x]+d elif not finished[y]: if directed_acyclic and dag: dag=False if cycle_detection: cd=(y,x) elif not finished[x]: finished[x]=True if euler_tour: et.append(~x) if lowlink: for y in self.graph[x]: if self.weighted: y,d=y if ps[x]==y: continue ll[x]=min(ll[x],order[y]) if x!=s: ll[ps[x]]=min(ll[ps[x]],ll[x]) if postorder or topological_sort: post.append(x) if subtree_size: for y in self.graph[x]: if self.weighted: y,d=y if y==ps[x]: continue ss[x]+=ss[y] if bipartite_graph: bg_=bg bg=[[[],[]] for i in range(cnt+1)] for tpl in self.edges: i,j=tpl[:2] if self.weighted else tpl if not bg_[i][1]^bg_[j][1]: bg[bg_[i][0]]=False for x in range(self.V): if bg[bg_[x][0]]: bg[bg_[x][0]][bg_[x][1]].append(x) retu=() if bipartite_graph: retu+=(bg,) if cycle_detection: if dag: cd=[] else: y,x=cd cd=self.Route_Restoration(y,x,ps) retu+=(cd,) if directed_acyclic: retu+=(dag,) if euler_tour: retu+=(et,) if linked_components: retu+=(lc,) if lowlink: retu=(ll,) if parents: retu+=(ps,) if postorder: retu+=(post,) if preorder: retu+=(pre,) if subtree_size: retu+=(ss,) if topological_sort: if dag: tp_sort=post[::-1] else: tp_sort=[] retu+=(tp_sort,) if unweighted_dist: retu+=(uwd,) if weighted_dist: retu+=(wd,) if len(retu)==1: retu=retu[0] return retu N,M=map(int,readline().split()) edges=[] se=set() for _ in range(M): g,r=map(int,readline().split()) g-=1 se.add(g) for h in map(int,readline().split()): h-=1 edges.append((h,g)) inf=1<<60 G=Graph(N,edges=edges,directed=True,inf=inf) ans=0 idx=[None]*N scc=G.SCC()[0] l=len(scc) points=[] for i in range(l): if len(scc[i])>=2: for x in scc[i]: points.append(x) ans=G.MIV_DFS(initial_vertices=points,unweighted_dist=True).count(inf) print(ans)