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[10002];
int main()
{
    LL n,i,x,y;
    while(scanf("%lld",&n)>0)
    {
        LL max1=-1;
        for(i=1;i<=n;i++)
        {
            scanf("%lld%lld",&x,&y);
            a[i]=x-y;
        }
        sort(a+1,a+1+n);
        max1=a[n];
        LL sum=0;
        LL hxl=a[n];
        for(i=1;i<=n-1;i++)
        {
            sum=sum+a[i];
            hxl=(hxl+a[i])%2;
        }
        if(max1>sum || hxl==1) printf("NO
");
        else printf("YES
");
    }
    return 0;
}