#include <bits/stdc++.h>
using namespace std;

typedef long long int item;

long long int n, m, a, b;

pair <long long int, long long int> calc(long long int nab) {
    long long int lo = 0;
    long long int hi = (a + b) / m + 1;
    long long int x = -1;

    while (lo <= hi) {
        long long int mid = (lo + hi) / 2;

        if (mid * m < nab) {
            x = mid;
            lo = mid + 1;
        }
        else {
            hi = mid - 1;
        }
    }
    long long int xab = x + 1;
    long long int yab;
    if (xab % 2 == 0) {
        yab = m - (nab - x * m) + 1;
    }    
    else {
        yab = nab - x * m;
    }

    return make_pair(xab, yab);
}

int main() {
    int T;
    cin >> T;
    while (T--) {
        cin >> n >> m >> a >> b;

        pair <long long int, long long int> A;
        pair <long long int, long long int> B;

        A = calc(a);
        B = calc(a+b);

        long long int answer = 0;

        answer = abs(A.first - B.first) + abs(A.second - B.second);

        cout << answer << endl;
    }
}