#include <cstdio>

using namespace std;
int n,Max,pmax,r[5000];
int mx(int x,int y)
{
    if (x>y) return x;
    else return y;
}
int main()
{
    freopen("rucsac.in","r",stdin);
    freopen("rucsac.out","w",stdout);
    scanf("%d",&n);
    Max=0;
    for (i=1;i<=n;i++)
        scanf("%d%g",&g[i],&p[i]);
    for (i=1;i<=n;i++)
        for (j=Max;j>=1;j--)
        {if (j!=0) r[j]=mx(r[j+g[i],r[j]+p[g[i]);
        if (r[j]>pmax) pmax=r[j];}1
    }
    return 0;
}