#include <bits/stdc++.h>

using namespace std;

int main() {

    int n,t;

    while(cin>>n>>t){

        int dp[n][2],a[n],b[n];

        for(int i=0;i<n;i++){

            cin>>a[i]>>b[i];

            if(i==0){

                dp[i][0]=abs(a[i]-t);

                dp[i][1]=abs(b[i]-t);

            }else{

                dp[i][0]=min(abs(a[i]-a[i-1])+dp[i-1][0],abs(a[i]-b[i-1])+dp[i-1][1]);

                dp[i][1]=min(abs(b[i]-a[i-1])+dp[i-1][0],abs(b[i]-b[i-1])+dp[i-1][1]);

            }

        }

        cout<<min(dp[n-1][0],dp[n-1][1]);

    }

    return 0;

}