def maximize_exhibition_value(N, artworks):
artworks.sort()
max_value = float('-inf')
current_sum = 0
left = 0
for right in range(N):
current_sum += artworks[right][1]
A_max = artworks[right][0]
A_min = artworks[left][0]
current_value = current_sum - (A_max - A_min)
max_value = max(max_value, current_value)
while left < right and (current_sum - artworks[left][1]) - (artworks[right][0] - artworks[left + 1][0]) >= current_value:
current_sum -= artworks[left][1]
left += 1
A_min = artworks[left][0]
current_value = current_sum - (A_max - A_min)
max_value = max(max_value, current_value)
return max_value
N = int(input())
artworks = []
for _ in range(N):
A, B = map(int, input().split())
artworks.append((A, B))
result = maximize_exhibition_value(N, artworks)
print(result)
