#include<iostream>
using namespace std;
int a,b,n,i,j;
long long w[12345],h[12345],sum,maxs;
int main () {
	cin>>n;
	for(i=1;i<=n;i++){
		cin>>w[i]>>h[i];
	}
	for(i=1;i<=n;i++){
		sum=0;
		sum=sum+w[i];
		for(j=i+1;j<=n;j++){
			if(h[i]==h[j]) sum=w[j]+sum;		
		}
		if(sum>maxs)
			{maxs=sum; sum=0;}
	}
	cout<<maxs<<endl;
return 0;
}
/*
8 
700 1000
1024 768
1600 600
800 1000
1280 768
600 1000
1023 767
1279 767
6 
700 1000
1024 768
1600 600
800 1000
1280 768
600 1000
*/
