/**************************************************************

    Problem: 4247

    User: yekehe

    Language: C++

    Result: Accepted

    Time:2728 ms

    Memory:17516 kb

****************************************************************/

#include <cstdio>

#include <algorithm>

#include <cstring>

using namespace std;

char tc()

{

    static char fl[],*A=fl,*B=fl;

    return A==B&&(B=(A=fl)+fread(fl,,,stdin),A==B)?EOF:*A++;

}

int read()

{

    char c;while(c=tc(),(c<''||c>'')&&c!='-');

    int x=,y=;c=='-'?y=-:x=c-'';

    while(c=tc(),c>=''&&c<='')x=x*+c-'';

    return x*y;

}

const int MAXN=;

int N,f[MAXN][MAXN];

struct node{

    int x,y;

}a[MAXN];

int cmp(node x,node y){return x.x>y.x;}

int main()

{

//  freopen("x.txt","r",stdin);

    N=read();

        for(int i=;i<=N;i++)a[i].x=read(),a[i].y=read();

    memset(f,-,sizeof(f));

    sort(a+,a+N+,cmp);

    f[][]=;

        for(int i=;i<=N;i++)

            for(int j=;j<=N;j++)

                f[i][j]=max(f[i-][j],f[i-][max(,j-a[i].x)+]+a[i].y);

    int ans=;

        for(int i=;i<=N;i++)ans=max(f[N][i],ans);

    printf("%d",ans);

    return ;

}