n,m=map(int,input().split())
g=[[]for i in range(n+1)]
for i in range(m):
    b,c=map(int,input().split())
    g[c]+=b,

q=list(range(1,n+1))

v=[0]*-~n
while q:
    c=q.pop()
    v[c]=max(v[c],c)
    for j in g[c]:
        if v[j]==0:
            q.append(j)
            v[j]=v[c]
v=[max(i,v[i])for i in range(n+1)]
print(sum(v))