zoj Gao The Sequence

Gao The Sequence

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Time Limit: 2 Seconds      Memory Limit: 65536 KB

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You are given a sequence of integers, A1,A2,...,An. And you are allowed a manipulation on the sequence to transform the origin sequence into another sequence B1,B2,...,Bn(Maybe the two sequences are same ). The manipulation is specified as the following three steps:

1.Select an integer Ai and choose an arbitrary positive integer delta as you like.

2.Select some integers Aj satisfying j < i, let's suppose the selected integers are Ak1,Ak2,...,Akt , then subtract an arbitrary positive integer Di from Aki (1 ≤ i ≤ t) as long as sum(Di) = delta.

3.Subtract delta from Ai.

The manipulation can be performed any times. Can you find a way to transform A1,A2,...,An to B1,B2,...,Bn ?

Input

The input consist of multiple cases. Cases are about 100 or so. For each case, the first line contains an integer N(1 ≤ N ≤ 10000) indicating the number of the sequence. Then followed by N lines, ith line contains two integers Ai and Bi (0 ≤ Bi ≤ Ai ≤ 4294967296).

Output

Output a single line per case. Print "YES" if there is a certain way to transform Sequence A into Sequence B. Print "NO" if not.

Sample Input

3
3 2
4 2
5 2
3
2 0
7 1
3 1

Sample Output

YES
NO

 #include<iostream>
 #include<stdio.h>
 #include<cstring>
 #include<cstdlib>
 #include<algorithm>
 using namespace std;
 typedef long long LL;

 LL a[];
 int main()
 {
     LL n,i,x,y;
     while(scanf("%lld",&n)>)
     {
         LL max1=-;
         for(i=;i<=n;i++)
         {
             scanf("%lld%lld",&x,&y);
             a[i]=x-y;
         }
         sort(a+,a++n);
         max1=a[n];
         LL sum=;
         LL hxl=a[n];
         for(i=;i<=n-;i++)
         {
             sum=sum+a[i];
             hxl=(hxl+a[i])%;
         }
         if(max1>sum || hxl==) printf("NO\n");
         else printf("YES\n");
     }
     return ;
 }