#include <bits/stdc++.h>
using namespace std;
#define modulo 1000000007
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 10000000000000000

int main(){
	
	int N;
	cin>>N;
	
	vector<long long> A(N),B(N);
	
	for(int i=0;i<N;i++){
		long long a,b;
		cin>>a>>b;
		A[i] = a-b;
		B[i] = b-a;
	}
	
	vector<long long> S1(N+1,0),S2(N+1,0);
	
	for(int i=1;i<=N;i++){
		S1[i] = S1[i-1] + A[i-1];
		S2[i] = S2[i-1] + B[i-1];
	}
	
	long long ans = -Inf;
	
	for(int i=0;i<=N;i++){
		ans = max(ans,S1[i] + S2[N] - S2[i]);
	}
	
	cout<<ans<<endl;

	return 0;
}