class Imos_1:
    def __init__(self,N):
        self.len=N
        self.list=[0]*(N+1)

    def Add(self,F,T,C=1):
        self.list[F]+=C
        self.list[T+1]-=C

    def Cumulative_Sum(self):
        Y=[0]*(self.len)
        S=0
        for i in range(self.len):
            S+=self.list[i]
            Y[i]=S

        return Y

N=int(input())

G=10**5
K=Imos_1(2*G+1)
for _ in range(N):
    x,r=map(int,input().split())
    K.Add(x-r+G,x+r+G)
print(max(K.Cumulative_Sum()))