import sys
input = sys.stdin.readline
from collections import *

def bfs(s):
    if ma[s]!=-1:
        return
    
    q = deque([s])
    ma[s] = s
    
    while q:
        v = q.popleft()
        
        for nv in G[v]:
            if ma[nv]==-1:
                ma[nv] = s
                q.append(nv)

N, M = map(int, input().split())
BC = [tuple(map(int, input().split())) for _ in range(M)]
l = []

for B, C in BC:
    l.append(B-1)
    l.append(C-1)

l = list(set(l))
l.sort()
idx = defaultdict(int)

for i in range(len(l)):
    idx[l[i]] = i

G = [[] for _ in range(len(l))]

for B, C in BC:
    G[idx[C-1]].append(idx[B-1])

ma = [-1]*len(l)

for i in range(len(l)-1, -1, -1):
    bfs(i)

ans = N*(N+1)//2

for li in l:
    ans -= li
    ans += l[ma[idx[li]]]

print(ans)