#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
 
struct node
{
	long long x,y;
	node(long long x1,long long y1)
	{
		x=x1;
		y=y1;
	}
};
 
bool comp(node*a,node*b)
{
	return a->x < b->x;
}
 
int main() {
 
	long long n;
	cin>>n;
 
	vector<node*> V;
 
	for(long long i=0;i<n;i++)
	{
		long long a,d;
		cin>>a>>d;
		V.push_back(new node(a,d));
	}
 
	sort(V.begin(),V.end(),comp);
 
	long long currentTime=0;
	long long reward=0;
	for(long long i=0;i<n;i++)
	{
		currentTime+=V[i]->x;
		reward += V[i]->y - currentTime;
	}
 
	cout<<reward<<endl;
 
	return 0;
}

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Mwo2IDEwCjggMTUKNSAxMg==

3
6 10
8 15
5 12