function activityNotifications (expenditure, d) {

    // Number of notifications
    let n = 0

    // Set midpoints for median calculation
    let [ i1, i2 ] = [ Math.floor((d-1)/2), Math.ceil((d-1)/2) ]
    let m1, m2, m

    // Initialize count sorted subarray
    let cs = new Array(201).fill(0)
    for (let i = d-1; i >= 0; i--) cs[expenditure[i]]++

    // Iterate through expenditures
    for (let i = d, l = expenditure.length; i < l; i++) {

        // Find median
        for (let j = 0, k = 0; k <= i1; k += cs[j], j++) m1 = j
        for (let j = 0, k = 0; k <= i2; k += cs[j], j++) m2 = j
        let m = (m1 + m2) / 2

        // Check if notification is given
        if (expenditure[i] >= m * 2) n++

        // Replace subarray elements
        cs[expenditure[i-d]]--
        cs[expenditure[i]]++
    }

    return n
}