import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
public class Main {
int N
= Integer.
parseInt(br.
readLine())+1; int arr[] = new int[N];
int weight[] = new int[N];
for(int i = 1; i < N ;i++) {
int a
= Integer.
parseInt(st.
nextToken()); int b
= Integer.
parseInt(st.
nextToken()); arr[i] = a;
weight[i] = b;
}
for(int i = 1; i < N; i++) {
if(i+arr[i] <= N) {
name(weight, arr, N, i+arr[i], weight[i]);
}
}
}
public static int max
= Integer.
MIN_VALUE; public static void name(int weight[],int arr[],int N, int date, int total ) {
if(max < total) {
max = total;
}
for(int i = date ; i < N; i++) {
if(i+arr[i] <= N) {
name(weight,arr, N, i+arr[i], total+weight[i]);
}
}
}
}
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