import sys
input = sys.stdin.readline
from operator import itemgetter

N,M=map(int,input().split())
E=dict()

for i in range(M):
    x,y=map(int,input().split())
    if y in E:
        E[y].append(x)
    else:
        E[y]=[x]

USESET=set()
SCORE=N*(N+1)//2

KEYS=sorted(E.keys(),reverse=True)

for i in KEYS:
    if i in USESET:
        continue

    Q=[i]
    while Q:
        x=Q.pop()
        if not (x in E):
            continue
        for to in E[x]:
            if to in USESET:
                continue
            else:
                USESET.add(to)
                if i>to:
                    SCORE+=i-to
                Q.append(to)

print(SCORE)