import sys readline=sys.stdin.readline from collections import deque class Graph: def __init__(self,V,edges=None,graph=None,directed=False,weighted=False,inf=float("inf")): self.V=V self.directed=directed self.weighted=weighted self.inf=inf if graph!=None: 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)) """ else: 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) def SIV_BFS(self,s,bfs_tour=False,bipartite_graph=False,linked_components=False,parents=False,unweighted_dist=False,weighted_dist=False): seen=[False]*self.V seen[s]=True if bfs_tour: bt=[s] if linked_components: lc=[s] if parents: ps=[None]*self.V if unweighted_dist or bipartite_graph: uwd=[self.inf]*self.V uwd[s]=0 if weighted_dist: wd=[self.inf]*self.V wd[s]=0 queue=deque([s]) while queue: x=queue.popleft() for y in self.graph[x]: if self.weighted: y,d=y if not seen[y]: seen[y]=True queue.append(y) if bfs_tour: bt.append(y) if linked_components: lc.append(y) if parents: ps[y]=x if unweighted_dist or bipartite_graph: uwd[y]=uwd[x]+1 if weighted_dist: wd[y]=wd[x]+d if bipartite_graph: bg=[[],[]] for tpl in self.edges: i,j=tpl[:2] if self.weighted else tpl if uwd[i]==self.inf or uwd[j]==self.inf: continue if not uwd[i]%2^uwd[j]%2: bg=False break else: for x in range(self.V): if uwd[x]==self.inf: continue bg[uwd[x]%2].append(x) retu=() if bfs_tour: retu+=(bt,) if bipartite_graph: retu+=(bg,) if linked_components: retu+=(lc,) if parents: retu+=(ps,) if unweighted_dist: retu+=(uwd,) if weighted_dist: retu+=(wd,) if len(retu)==1: retu=retu[0] return retu def Warshall_Floyd(self,route_restoration=False): dist=[[self.inf]*self.V for i in range(self.V)] for i in range(self.V): dist[i][i]=0 if route_restoration: parents=[[j for j in range(self.V)] for i in range(self.V)] for i,j,d in self.edges: if i==j: continue if dist[i][j]>d: dist[i][j]=d if route_restoration: parents[i][j]=i if not self.directed and dist[j][i]>d: dist[j][i]=d if route_restoration: parents[j][i]=j for k in range(self.V): for i in range(self.V): for j in range(self.V): if dist[i][j]>dist[i][k]+dist[k][j]: dist[i][j]=dist[i][k]+dist[k][j] if route_restoration: parents[i][j]=parents[k][j] for i in range(self.V): if dist[i][i]<0: for j in range(self.V): if dist[i][j]!=self.inf: dist[i][j]=-self.inf if route_restoration: for i in range(self.V): if dist[i][i]==0: parents[i][i]=None return dist,parents else: return dist N,M=map(int,readline().split()) edges=[] for m in range(M): a,b=map(int,readline().split()) a-=1;b-=1 edges.append((a,b,1)) inf=1<<60 G=Graph(N,edges=edges,inf=inf,weighted=True) dist=G.Warshall_Floyd() ans=0 for i in range(N): for j in range(i+1,N): for k in range(j+1,N): if not 2 in (dist[i][j],dist[i][k],dist[j][k]): ans+=1 print(ans)