// #include <me>
#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define pb push_back
#define int long long
const int N = 3e5 + 5, M = 1e9 + 7, LG = 20;
int n , T , x , y;
void solve(){
cin >> n >> T;
cin >> x >> y;
int ans = 1e18;
int a = x%T , b = y%T;
ans = min(ans , (a + b) - 2 * ((a + b)/2));
a = x%T - T , b = y%T;
ans = min(ans , (a + b) - 2 * ((a + b)/2));
a = x%T , b = y%T - T;
ans = min(ans , (a + b) - 2 * ((a + b)/2));
a = x%T - T , b = y%T - T;
ans = min(ans , (a + b) - 2 * ((a + b)/2));
cout << ans << endl;
}
signed main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int ts = 1;
// cin >> ts;
while(ts--){
solve();
}
}
