Problem:
Score : 200 points

Problem Statement

A group of people played a game. All players had distinct scores, which are positive integers.

Takahashi knows N facts on the players' scores. The i-th fact is as follows: the A_i-th highest score among the players is B_i.

Find the maximum possible number of players in the game.

Constraints

1 \leq N \leq 10^5

1 \leq A_i \leq 10^9(1\leq i\leq N)

0 \leq B_i \leq 10^9(1\leq i\leq N)

If i ≠ j, A_i ≠ A_j.

There exists a possible outcome of the game that are consistent with the facts.

All input values are integers.

Inputs

Input is given from Standard Input in the following format:

N
A_1 B_1
:
A_N B_N

Outputs

Print the maximum possible number of players in the game.

Sample Input 1

3
4 7
2 9
6 2

Sample Output 1

8

The maximum possible number of players is achieved when, for example, the players have the following scores: 12,9,8,7,5,2,1,0.

Sample Input 2

5
1 10
3 6
5 2
4 4
2 8

Sample Output 2

7

Sample Input 3

2
1 1000000000
1000000000 1

Sample Output 3

1000000001

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;

public class Main {               
    
  public static void main(String[] args) {     
     
      Scanner sc = new Scanner(System.in);                                     
                                               
      int N = sc.nextInt();
      
      int a[] = new int[N];
      int b[] = new int[N];
      
      HashMap<Integer,Integer> map = new HashMap<Integer,Integer>();
      
      for(int i = 0;i < N;i++){
            a[i] = sc.nextInt();
            b[i] = sc.nextInt();      
            map.put(a[i],b[i]);
      }
      
      Arrays.sort(a);
      
      int amin = a[0];
      int amax = a[a.length - 1];
            
      int base = amax - amin + 1;
      
      int bmin = map.get(amax);
      int bmax = map.get(amin);      
      
      int max_value = (int) Math.pow(10,9);
      int min_value = 0;      
     
      int bstart = 0;
      int astart = 1;
      
      int bminside_plus = bmin - bstart;      
      int bmaxside_plus = Math.min(max_value - bmax,amin - astart);
      
      System.out.println(bminside_plus + base + bmaxside_plus);
      
  }          
}