N,M = map(int,input().split())
from collections import defaultdict
G = defaultdict(list)
for _ in range(M):
    b,c = map(int,input().split())
    G[c].append(b)
l = sorted(G)
memo = defaultdict(int)
stack = []
dp = defaultdict(int)
for v in reversed(l):
    if memo[v] == 1:continue
    dp[v] = v
    memo[v] = 1
    stack = [v]
    while stack:
        now = stack.pop()
        for u in G[now]:
            if memo[u] == 0:
                stack.append(u)
                dp[u] = max(u,dp[v])
                memo[u] = 1
ans = N * (N + 1) // 2
for k in dp:
    ans += dp[k] - k
print(ans)
#print(dp)