Shared code

import sys

input = sys.stdin.readline


def solve(n, tasks):
    # we can see that deadline doesnt matter cuz we always have to do the task
    tasks.sort()
    ans = 0
    curr_time = 0
    for duration, deadline in tasks:
        curr_time += duration
        ans += deadline - curr_time
    print(ans)


def main():
    n = int(input())
    tasks = [list(map(int, input().split())) for _ in range(n)]
    solve(n, tasks)


main()