10763 - Foreign Exchange

#include<iostream>
#include<algorithm>
#define M 500000
using namespace std;

int domestic[M],foreign[M];
bool possible(int);

int main()
{
    int n,i;
    //freopen("in.txt","r",stdin);

    while(scanf("%d",&n)&&n)
    {
        for(i = 0;i<n;i++)
            scanf("%d%d",&domestic[i],&foreign[i]);

        if(possible(n))
            printf("YES\n");
        else
            printf("NO\n");
    }
    return 0;
}

bool possible(int n)
{
    int i;

    sort(domestic,domestic+n);
    sort(foreign,foreign+n);

    for(i = 0;i < n;i++)
        if(domestic[i]^foreign[i])
            return false;
    return true;
}