# include<iostream>
# include<algorithm>
using namespace std;
struct monitors
{
	long long  a,b;
};

bool operator<(monitors x, monitors y)
{
	return x.b<y.b;
}

monitors c[100002];
int main()
{
	int n;
	cin>>n;
	for(int i=0; i<n; i++)
		cin>>c[i].a>>c[i].b;
	
	sort(c,c+n);
	long long sum=0,maxs=0;
	
	for(int i=0; i<n; i++)
	{
	
		while(i<n && c[i].b==c[i+1].b) {sum+=c[i].a; i++;}
		sum+=c[i].a;

		if(maxs<sum) maxs=sum;
		sum=0;
		
	}
	
	cout<<maxs<<endl;
	
	
	
	return 0;
}
