import java.util.Arrays;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.OutputStream;
public class art {
private static class Kattio extends PrintWriter {
public Kattio(InputStream i) {
super(new BufferedOutputStream(System.out));
r = new BufferedReader(new InputStreamReader(i));
}
public Kattio(InputStream i, OutputStream o) {
super(new BufferedOutputStream(o));
r = new BufferedReader(new InputStreamReader(i));
}
public boolean hasMoreTokens() {
return peekToken() != null;
}
public int getInt() {
return Integer.parseInt(nextToken());
}
public double getDouble() {
return Double.parseDouble(nextToken());
}
public long getLong() {
return Long.parseLong(nextToken());
}
public String getWord() {
return nextToken();
}
private BufferedReader r;
private String line;
private StringTokenizer st;
private String token;
private String peekToken() {
if (token == null)
try {
while (st == null || !st.hasMoreTokens()) {
line = r.readLine();
if (line == null)
return null;
st = new StringTokenizer(line);
}
token = st.nextToken();
} catch (IOException e) {
}
return token;
}
private String nextToken() {
String ans = peekToken();
token = null;
return ans;
}
}
private static final class Artwork {
public final long a;
public final int b;
public Artwork(long a, int b) {
this.a = a;
this.b = b;
}
}
private static int clamp(long x,int min,int max) {
if (x < min) return min;
if (x > max) return max;
return (int) x;
}
public static void main(String[] args) {
try (Kattio io = new Kattio(System.in, System.out)) {
int n = io.getInt();
Artwork[] artworks = new Artwork[n];
for (int i=0; i<n; ++i) {
artworks[i] = new Artwork(io.getLong(), io.getInt());
}
Arrays.sort(artworks, (t, o) -> clamp(t.a - o.a, -1, 1));
long[] f = new long[n+1];
f[0] = 0;
long minSoFar = (long) 4e18;
long result = 0;
for (int i=0; i<n; ++i) {
f[i+1] = f[i] + artworks[i].b;
result = Math.max(result, artworks[i].b);
long tmp = f[i+1] - artworks[i].a;
result = Math.max(result, tmp - minSoFar);
minSoFar = Math.min(minSoFar, f[i] - artworks[i].a);
}
io.println(result);
}
}
}
