Problem: p02948
Buggy submission (PyPy3 (2.4.0), verdict: Wrong Answer):

from collections import defaultdict,deque
from heapq import heappush, heappop
from bisect import *
import sys, random, itertools, math
sys.setrecursionlimit(10**5)
input = sys.stdin.readline
sqrt = math.sqrt
def LI(): return list(map(int, input().split()))
def LF(): return list(map(float, input().split()))
def LI_(): return list(map(lambda x: int(x)-1, input().split()))
def II(): return int(input())
def IF(): return float(input())
def LS(): return list(map(list, input().split()))
def S(): return list(input().rstrip())
def IR(n): return [II() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def FR(n): return [IF() for _ in range(n)]
def LFR(n): return [LI() for _ in range(n)]
def LIR_(n): return [LI_() for _ in range(n)]
def SR(n): return [S() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
mod = 1000000007
inf = float('INF')


def A():
    a, b = LI()
    print(max(a + b, a - b, a * b))
    return


def B():
    k, x = LI()
    ans = []
    for i in range(x - k + 1, x + k):
        ans.append(i)
    print(*ans)
    return


def C():
    n = II()
    d = defaultdict(int)
    for _ in range(n):
        s = S()
        s.sort()
        d[tuple(s)] += 1
    ans = 0
    for i in d.values():
        ans += i * (i - 1) 
    print(ans)
    return


def D():
    n, m = LI()
    ab = LIR(n)
    ab.sort(key=lambda x: (x[1], x[0]), reverse=True)
    ans = 0
    for i in range(n):
        if m >= ab[i][0]:
            ans += ab[i][1]
            m -= 1
    print(ans)
    return


def E():
    return


def F():
    return


if __name__ == '__main__':
    D()


Failing test case input:
3 5
4 3
4 1
2 2

Expected output:
6


Actual output:
5


Fixed submission (verdict: Accepted):

from collections import defaultdict,deque
from heapq import heappush, heappop
from bisect import *
import sys, random, itertools, math
sys.setrecursionlimit(10**5)
input = sys.stdin.readline
sqrt = math.sqrt
def LI(): return list(map(int, input().split()))
def LF(): return list(map(float, input().split()))
def LI_(): return list(map(lambda x: int(x)-1, input().split()))
def II(): return int(input())
def IF(): return float(input())
def LS(): return list(map(list, input().split()))
def S(): return list(input().rstrip())
def IR(n): return [II() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def FR(n): return [IF() for _ in range(n)]
def LFR(n): return [LI() for _ in range(n)]
def LIR_(n): return [LI_() for _ in range(n)]
def SR(n): return [S() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
mod = 1000000007
inf = float('INF')


def A():
    a, b = LI()
    print(max(a + b, a - b, a * b))
    return


def B():
    k, x = LI()
    ans = []
    for i in range(x - k + 1, x + k):
        ans.append(i)
    print(*ans)
    return


def C():
    n = II()
    d = defaultdict(int)
    for _ in range(n):
        s = S()
        s.sort()
        d[tuple(s)] += 1
    ans = 0
    for i in d.values():
        ans += i * (i - 1) 
    print(ans)
    return





def D():
    n, m = LI()
    q = []
    d = defaultdict(list)
    ans = 0
    for _ in range(n):
        a, b = LI()
        d[a].append(b)
    for i in range(m):
        for di in d[i+1]:
            heappush(q, -di)
        if q:
            ans -= heappop(q)
    print(ans)
    return


def E():
    return


def F():
    return


if __name__ == '__main__':
    D()