n, m = map(int, input().split())

max_c = {}

for _ in range(m):
    b, c = map(int, input().split())
    if c > b:
        if b not in max_c or c > max_c[b]:
            max_c[b] = c

keys = sorted(max_c.keys(), reverse=True)

max_reachable = {}

for k in keys:
    c = max_c[k]
    if c > k:
        if c in max_reachable:
            max_reachable[k] = max_reachable[c]
        else:
            max_reachable[k] = c
    else:
        max_reachable[k] = k

delta = 0
for k in keys:
    if max_reachable[k] > k:
        delta += (max_reachable[k] - k)

s = n * (n + 1) // 2
print(s + delta)