CUBE-103: Lock On!

#include <bits/stdc++.h>
using namespace std;
const int INF=1e9;
using pii=pair<int,int>;
int main(){
    int n,p;
    scanf("%d%d",&n,&p);
    vector <pii> g;
    for(int i=0;i<n;i++){
        int a,b,k;
        scanf("%d%d",&a,&b);
        if(a>b) {
            k=a;
            a=b;
            b=k;
        }
        g.push_back({a,1});//add
        g.push_back({b,2});//remove
    }
    sort(g.begin(),g.end());
    int cnt=0,s=-1,e=-1;
    for(auto i:g){
        if(i.second==1){
            cnt++;
            if(cnt==n and s==-1) s=i.first;
        }
        else{
            cnt--;
            if(cnt==n-1 and s!=-1) e=i.first;
        }
    }
    if(s==-1) printf("-1");
    else if(s<=p and p<=e) printf("0");
    else if(p<s) printf("%d",s-p);
    else printf("%d",p-e);

    return 0;
}