#include <iostream>
#include <algorithm>

using namespace std;
const int N=50005;
struct Row{
    int w,s;
    bool operator<(const Row &b)const{
        return (s+w)<(b.s+b.w);
    }
}row[N];
int s[N],w[N];

int main()
{
    int n;
    cin>>n;
    for(int i=0;i<n;i++){
        int s,w;
        cin>>w>>s;
        row[i]={w,s};
    }
    sort(row,row+n);
    int sum=0;
    int Max=-1e9;
    for(int i=0;i<n;i++)
    {

        if(sum-row[i].s>Max) Max=sum-row[i].s;
        sum+=row[i].w;
    }
    cout<<Max;
    return 0;
}