import sys, time, random, heapq
from collections import deque, Counter, defaultdict
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 63 - 1
mod = 998244353
#https://tjkendev.github.io/procon-library/python/convex_hull_trick/deque.html
deq = deque()
def check(f1, f2, f3):
    return (f2[0] - f1[0]) * (f3[1] - f2[1]) >= (f2[1] - f1[1]) * (f3[0] - f2[0])
def f(f1, x):
    return f1[0]*x + f1[1]

# add f_i(x) = a*x + b
def add_line(a, b):
    f1 = (a, b)
    while len(deq) >= 2 and check(deq[-2], deq[-1], f1):
        deq.pop()
    deq.append(f1)

# min f_i(x)
def query(x):
    while len(deq) >= 2 and f(deq[0], x) >= f(deq[1], x):
        deq.popleft()
    return f(deq[0], x)

n, m = mi()
AD = [li() for _ in range(n)]
plus = []
minus = []

for a, d in AD:
    if d > 0:
        plus.append((a, d))
    else:
        minus.append((a, d))

p = [-inf] * (m + 1)
p[0] = 0
for a, d in plus:
    add_line(-d, -2 * a + d)
if plus:
    for i in range(1, m + 1):
        p[i] = -query(i) * i // 2


q = [-inf] * (m + 1)
q[0] = 0
H = []

for a, d in minus:
    heapq.heappush(H, (-a, d))

for i in range(1, m + 1):
    a, d = heapq.heappop(H)
    a = -a
    q[i] = q[i - 1] + a
    heapq.heappush(H, (-(a + d), d))
ans = -inf
maxi = -1
for i in range(0, m + 1):
    if ans <= p[i] + q[m - i]:
        ans = max(ans, p[i] + q[m - i])
        maxi = i

print(ans)
print(maxi, file=sys.stderr)