#include<iostream>
#include<cmath>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
struct node{
	int g,x;
}a[2005];
int n,ans=-100000000;
int dp[2005][2005];
bool cmp(node x,node y){
	return x.g>y.g;
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i].g>>a[i].x;
	}
	sort(a+1,a+1+n,cmp);
	for(int i=0;i<=n;i++){
		dp[0][i]=-100000000;
		dp[i][n+1]=-100000000;
	}
	dp[0][1]=0;
	for(int i=1;i<=n;i++){
		for(int j=0;j<=n;j++){
			dp[i][j]=max(dp[i-1][j],dp[i-1][max(j-a[i].g,0)+1]+a[i].x);
		}
	}
	for(int i=0;i<=n;i++) {
		ans=max(ans,dp[n][i]);
	}
	cout<<ans;
	return 0;
}