#include <iostream>
#include <vector>
#include <cmath>
#include <iomanip>

double S(double x, double R)
{
    return R * R / 2.0 * std::atan2(std::sqrt(R * R - x * x), x) - 0.5 * x * std::sqrt(R * R - x * x);
}

 
double circleRectArea(double x, double y, double R)
{
    double x0 = std::min(std::fabs(x), std::sqrt(std::max(0.0, R * R - y * y)));
    double x1 = std::min(std::fabs(x), R);
    double sx = (x < 0) ? -1 : 1;
    double sy = (y < 0) ? -1 : 1;
    return sx * x0 * y + sx * sy * (S(x0, R) - S(x1, R));
}

double circleRectArea(double x1, double y1, double x2, double y2, double R)
{
    return circleRectArea(x2, y2, R) - circleRectArea(x2, y1, R) - circleRectArea(x1, y2, R) + circleRectArea(x1, y1, R);
}

int main()
{
    int n, r, w, h;
    std::cin >> n >> r >> w >> h;
   
    double tot = 0.0;
    
    for(int i=0; i<n; i++)
    {
        int x, y, val;
        std::cin >> x >> y >> val;
        
        double area = circleRectArea(w-x, h-y, -x, -y, r);
        tot += area * val;
    }
    
    double answer = tot / double(h*w);
    std::cout << std::setprecision(30) << answer << std::endl;
}