BOJ-2460

// https://www.acmicpc.net/problem/2460

const fs = require("fs");
const stations = fs.readFileSync("/dev/stdin").toString().trim().split("\n");

let cnt = 0;
let maxCnt = 0;

stations.forEach((station) => {
  const [out, on] = station.split(" ");

  cnt += on - out;

  if (cnt > maxCnt) {
    maxCnt = cnt;
  }
});

console.log(maxCnt);