题解

#include<bits/stdc++.h>
using namespace std;
int n,m,ans=0x3f3f3f3f,l,r,minn,maxn,flag;
int a[1005];
int main()
{
	cin>>n>>m;
	for(int i=1;i<=n;i++)
	{
		scanf("%d%d",&l,&r);
		if(l>r)swap(l,r);
		for(int j=l;j<=r;j++)
		{
			a[j]++;
		}
		minn=min(minn,l);
		maxn=max(maxn,r);
	}
	for(int i=minn;i<=maxn;i++)
	{
		if(a[i]==n)
		{
			ans=min(ans,abs(i-m));
			flag=1;
		}
	}
	if(flag==0)cout<<-1<<endl;
	else cout<<ans<<endl;
	return 0;
}