cases = int(input())
 
events = []
while cases > 0:
  cases -= 1
  event = input().split(" ")
  events.append((int(event[0]), int(event[1])))
 
events.sort(key=lambda x: x[1])
time = {}
for e in events:
  if e[1] in time:
    time[e[1]].append(e[0])
  else:
    time[e[1]] = [e[0]]
 
events = []
for v in time.values():
  events.append(sum(v))
 
Max = 0
count = 0
for e in events:
  count += e
  Max = max(Max, count)
 
# print(events)
print(Max)
 

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NAoxIDMKMSAyCi0xIDQKLTEgNQ==

4
1 3
1 2
-1 4
-1 5