from collections import defaultdict

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

operations = []
s = set()

for _ in range(m):
    b, c = map(int, input().split())
    operations.append((b, c))
    s.add(b)
    s.add(c)

sorted_list = sorted(s, reverse=True)

b_to_c = defaultdict(list)
for b, c in operations:
    b_to_c[b].append(c)

max_reach = {x: x for x in sorted_list}

for x in sorted_list:
    cs = b_to_c.get(x, [])
    if not cs:
        continue
    current_max = max(max_reach.get(c, c) for c in cs)
    if current_max > max_reach[x]:
        max_reach[x] = current_max

sum_increment = 0
for x in sorted_list:
    if 1 <= x <= n and max_reach[x] > x:
        sum_increment += (max_reach[x] - x)

initial_sum = n * (n + 1) // 2
print(initial_sum + sum_increment)