155B - Combination - CodeForces Solution

n = int(input())
l = []
for i in range(n):
	l.append(list(map(int, input().split())))
l.sort(key=lambda x: (-x[1], -x[0]))
c = 1
ind = 0
ans = 0
while c > 0 and ind < n:
	ans += l[ind][0]
	c += l[ind][1]
	ind += 1
	c -= 1
print(ans)