#include<iostream>
using namespace std;
struct monitor {
		long long shirina;
		long long visocina;
};
int n;
long long seg,result=0;
int main (){
cin>>n;
monitor vhod[n];
for(int i=0;i<n;i++){
	cin>>vhod[i].shirina>>vhod[i].visocina;
	seg=vhod[i].shirina;
	for(int j=0;j<i;j++){
			if(vhod[j].visocina==vhod[i].visocina){
				seg+=vhod[j].shirina;
			}
	}
	if(seg>result) result=seg;
}
cout<<result<<endl;
return 0;
}
