N,M=map(int,input().split())
g=dict()
e=[]
for i in range(M):
    b,c=map(int,input().split())
    e.append((c,b))
    g[c]=[]
for a,b in e:
    g[a].append(b)
e.sort(reverse=True)
to=dict()
ans=N*(N+1)//2

def dfs(cur,v):
    global ans
    for dst in g[cur]:
        if dst in to or dst>v:
            continue
        to[dst]=v
        ans+=v-dst
        if dst in g:
            dfs(dst,v)

for src,tmp in e:
    dfs(src,src)

print(ans)