#include <iostream>
#include <algorithm>
using namespace std;
int n;
struct arta
{
long long x, y;
}v[500005];
long long seg[2000005],lz[2000005];
void update( int nod , int st, int dr, int l ,int r , long long val )
{
if( l <= st && dr <= r )
{
lz[nod] += val ;
seg[nod] += val ;
}
else
if( l > dr || st > r )
return ;
else
{
int mij = ( st +dr ) / 2;
lz[nod*2] += lz[nod],seg[nod*2]+= lz[nod];
lz[nod*2+1] += lz[nod],seg[nod*2+1] += lz[nod];
lz[nod] = 0 ;
update(nod*2,st,mij,l,r,val) ;
update(nod*2+1,mij+1,dr,l,r,val);
seg[nod] = max( seg[nod*2],seg[nod*2+1]);
}
}
long long query(int nod ,int st , int dr ,int l , int r )
{
if( l <= st && dr <= r )
return seg[nod];
else
if( st > r || dr < l )
return -1e18;
else
{
int mij = ( st + dr ) / 2;
lz[nod*2] += lz[nod],lz[nod*2+1]+= lz[nod];
seg[nod*2] += lz[nod],seg[nod*2+1] += lz[nod];
lz[nod] = 0 ;
return max(query(nod*2,st,mij,l,r),query(nod*2+1,mij+1,dr,l,r));
}
}
bool tdl ( arta x , arta y )
{
return ( x.x < y.x);
}
int main()
{
cin >> n ;
for (int i = 1; i <= n ; i ++ )
cin >> v[i].x>>v[i].y;
sort(v+1,v+n+1,tdl);
long long ans = 0;
for ( int i = 1 ; i <= n ;i ++ )
{
update(1,1,n,1,i,v[i].y);
if ( i != 1 )
update(1,1,n,1,i - 1 ,-(v[i].x - v[i-1].x));
//cout << query(1,1,n,1,1)<< '\n';
ans = max ( ans , query(1,1,n,1,i));
}
cout << ans << '\n';
return 0;
}
