n, m = map(int, input().split())
operations = []
for _ in range(m):
    b, c = map(int, input().split())
    operations.append((b, c))

# Sort operations by C in descending order
operations.sort(key=lambda x: -x[1])

max_map = {}

for b, c in operations:
    current_b = max_map.get(b, b)
    current_c = max_map.get(c, c)
    if current_c > current_b:
        max_map[b] = current_c

total = n * (n + 1) // 2
sum_diff = 0
for key in max_map:
    sum_diff += (max_map[key] - key)

print(total + sum_diff)