Codeforces_116A

//Codeforces 116A
#include <iostream>
using namespace std;
int main()
{
    int n, out, in, a=0, max=0;
    cin >> n;
    for(int i=0;i<n;i++)
    {
        cin >> out >> in;
        a-=out;
        a+=in;
        if(a>max){max=a;}
    }
    cout << max;
    return 0;
}