#include <iostream>
#include <vector>
#include <algorithm>
#include <climits>
using namespace std;
class SegmentTree {
public:
SegmentTree(int size):size(size) {
tree.resize(4*size,LLONG_MIN);
}
void build(const vector<long long>& data,int node,int start,int end) {
if (start==end) {
tree[node]=data[start];
} else {
int mid=(start+end)/2;
build(data,2*node+1,start,mid);
build(data,2*node+2,mid+1,end);
tree[node]=max(tree[2*node+1],tree[2*node+2]);
}
}
void update(int idx,long long value,int node,int start,int end) {
if (start==end) {
tree[node]=value;
} else {
int mid=(start+end)/2;
if (start<=idx && idx<=mid) {
update(idx,value,2*node+1,start,mid);
} else {
update(idx,value,2*node+2,mid+1,end);
}
tree[node]=max(tree[2*node+1],tree[2*node+2]);
}
}
long long query(int l,int r,int node,int start,int end) {
if (r<start || l>end) return LLONG_MIN;
if (l<=start && end<=r) return tree[node];
int mid=(start+end)/2;
return max(query(l,r,2*node+1,start,mid),query(l,r,2*node+2,mid+1,end));
}
private:
vector<long long> tree;
int size;
};
int main() {
long long n;
cin>>n;
vector<pair<long long,long long>> art(n);
vector<long long> values(n);
for (long long i=0;i<n;++i) {
cin>>art[i].first>>art[i].second;
values[i]=art[i].second;
}
sort(art.begin(),art.end());
SegmentTree segmentTree(n);
segmentTree.build(values,0,0,n-1);
long long ans=LLONG_MIN;
for (int left=0;left<n;++left) {
long long sum=0;
long long min_size=art[left].first;
for (int right=left;right<n;++right) {
sum+=art[right].second;
long long max_size=art[right].first;
long long current_value=sum-(max_size-min_size);
ans=max(ans,current_value);
}
}
cout<<ans<<endl;
}
