import java.io.*;
import java.util.*;
public class art {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
PrintWriter pw = new PrintWriter(System.out);
long N = Long.parseLong(br.readLine());
long[][] artworks = new long[(int) N][2];
for (int i = 0; i < N; i++) {
StringTokenizer st = new StringTokenizer(br.readLine());
artworks[i][0] = Long.parseLong(st.nextToken());
artworks[i][1] = Long.parseLong(st.nextToken());
}
Arrays.sort(artworks, Comparator.comparingLong(a -> a[0]));
long max = Long.MIN_VALUE;
int l = 0;
long total = 0;
for (int r = 0; r < N; r++) {
total += artworks[r][1];
while (l <= r && total < (artworks[r][0] - artworks[l][0])) {
total -= artworks[l][1]; //update window
l++;
}
max = Math.max(max, total - (artworks[r][0] - artworks[l][0]));//find the new max of the window
}
pw.println(max);
pw.close();
}
}
