import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10 ** 7)

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

val = set()
for b, c in BC:
    val.add(b)
    val.add(c)

val = sorted(val)
vtoi = {v: i for i, v in enumerate(val)}
sz = len(val)
edge = [[] for _ in range(sz)]
for b, c in BC:
    s = vtoi[b]
    t = vtoi[c]
    edge[s].append(t)

vis = [0] * sz
goal = list(range(sz))


def dfs(s, p):
    vis[s] = 1
    for t in edge[s]:
        if vis[t]:
            goal[s] = max(goal[s], goal[t])
            continue
        if t == p:
            continue
        dfs(t, s)
        goal[s] = max(goal[s], goal[t])


for i in range(sz):
    if vis[i]:
        continue
    dfs(i, -1)

ans = N * (N + 1) // 2
for i, g in enumerate(goal):
    ans -= val[i]
    ans += val[g]
print(ans)