package Practice;

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.util.StringTokenizer;

public class B14501_1 { //Åð»ç(¹éÆ®·¡Å·)

static int N, temp, max;

static int[] T, P;

public static void main(String[] args) throws Exception {

// TODO Auto-generated method stub

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

N = Integer.parseInt(br.readLine());

T = new int[N];

P = new int[N];

for(int i = 0; i < N; i++) {

StringTokenizer st = new StringTokenizer(br.readLine());

T[i] = Integer.parseInt(st.nextToken());

P[i] = Integer.parseInt(st.nextToken());

}

max = 0;

Solve(0);

System.out.println(max);

}

public static void Solve(int index) {

if(index >= N) {

max = Math.max(max, temp);

return;

}

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

if(i + T[i] <= N) {

temp += P[i];

Solve(i + T[i]);

temp -= P[i];

}

}

max = Math.max(max, temp);

}

}