#include <bits/stdc++.h>

using i64 = long long;

constexpr int N = 1e5 + 5;
constexpr i64 INF = (1ll << 60);

int T, n, k, X, Y;
i64 x[N], y[N], sumX1[N], sumY1[N], sumX2[N], sumY2[N], tarL[N], tarR[N];

i64 upInt(i64 x, i64 y) {
    if (x % y == 0) return x / y;
    if (y < 0) x = -x, y = -y;

    if (x > 0) return x / y + 1;
    if (x == 0) return 0;
    if (x < 0) return x / y;
    return -1;
}

i64 downInt(i64 x, i64 y) {
    if (x % y == 0) return x / y;
    if (y < 0) x = -x, y = -y;

    if (x > 0) return x / y;
    if (x == 0) return 0;
    if (x < 0) return x / y - 1;
    return -1;
}

void solveX1() {

    for (int i = 0; i < n; i++) {
        // t * sumX1[n - 1] + sumX1[i] <= X
        
        if (sumX1[n - 1] == 0) {
            if (sumX1[i] > X) {
                tarL[i] = INF;
                tarR[i] = -INF;
            }
        }
        if (sumX1[n - 1] < 0) {
            tarL[i] = std::max(tarL[i], upInt(X - sumX1[i], sumX1[n - 1]));
        }
        if (sumX1[n - 1] > 0) {
            tarR[i] = std::min(tarR[i], downInt(X - sumX1[i], sumX1[n - 1]));
        }
    }
}

void solveX2() {

    for (int i = 0; i < n; i++) {
        // t * sumX2[n - 1] + sumX2[i] >= X
        
        if (sumX2[n - 1] == 0) {
            if (sumX2[i] < X) {
                tarL[i] = INF;
                tarR[i] = -INF;
            }
        }
        if (sumX2[n - 1] < 0) {
            tarR[i] = std::min(tarR[i], downInt(X - sumX2[i], sumX2[n - 1]));
        }
        if (sumX2[n - 1] > 0) {
            tarL[i] = std::max(tarL[i], upInt(X - sumX2[i], sumX2[n - 1]));
        }
    }
}

void solveY1() {
    for (int i = 0; i < n; i++) {
        // t * sumY1[n - 1] + sumY1[i] <= Y
        
        if (sumY1[n - 1] == 0) {
            if (sumY1[i] > Y) {
                tarL[i] = INF;
                tarR[i] = -INF;
            }
        }
        if (sumY1[n - 1] < 0) {
            tarL[i] = std::max(tarL[i], upInt(Y - sumY1[i], sumY1[n - 1]));
        }
        if (sumY1[n - 1] > 0) {
            tarR[i] = std::min(tarR[i], downInt(Y - sumY1[i], sumY1[n - 1]));
        }
    }
}

void solveY2() {

    for (int i = 0; i < n; i++) {
        // t * sumY2[n - 1] + sumY2[i] >= Y
        
        if (sumY2[n - 1] == 0) {
            if (sumY2[i] < Y) {
                tarL[i] = INF;
                tarR[i] = -INF;
            }
        }
        if (sumY2[n - 1] < 0) {
            tarR[i] = std::min(tarR[i], downInt(Y - sumY2[i], sumY2[n - 1]));
        }
        if (sumY2[n - 1] > 0) {
            tarL[i] = std::max(tarL[i], upInt(Y - sumY2[i], sumY2[n - 1]));
        }
    }
}

void solve() {

    std::cin >> n >> k >> X >> Y;
    for (int i = 0; i < n; i++) {
        tarL[i] = 0; tarR[i] = INF;
        std::cin >> x[i] >> y[i];
        std::tie(x[i], y[i]) = std::make_pair(x[i] + y[i], x[i] - y[i]);
    }

    sumX1[0] = x[0] - k; for (int i = 1; i < n; i++) sumX1[i] = sumX1[i - 1] + x[i] - k;
    sumX2[0] = x[0] + k; for (int i = 1; i < n; i++) sumX2[i] = sumX2[i - 1] + x[i] + k;
    sumY1[0] = y[0] - k; for (int i = 1; i < n; i++) sumY1[i] = sumY1[i - 1] + y[i] - k;
    sumY2[0] = y[0] + k; for (int i = 1; i < n; i++) sumY2[i] = sumY2[i - 1] + y[i] + k;

    std::tie(X, Y) = std::make_pair(X + Y, X - Y);

    if (X == 0 && Y == 0) {
        std::cout << "0" << "\n";
        return;
    }

    solveX1();
    solveX2();
    solveY1();
    solveY2();

    i64 ans = INF;
    for (int i = 0; i < n; i++) {
        if (tarL[i] > tarR[i]) continue;
        ans = std::min(ans, tarL[i] * n + i + 1);
    }

    if (ans == INF) std::cout << "-1" << "\n";
    else std::cout << ans << "\n";
}

int main() {

    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    std::cin >> T;
    while (T--) solve();

    return 0;
}