using Printf function score(xy, x², y²) if x² == 0 return 0 end coef = xy / x² return y² + (coef^2 * x²) - (2coef * xy) end function main() N = parse(Int, readline()) H = parse(Int, readline()) x = zeros(Int, N) y = zeros(Int, N) for i in 1:N x[i], y[i] = parse.(Int, split(readline())) end slopes = (y .- (H // 2)) .// x slopes_perm = sortperm(slopes, rev=true) x_perm = sortperm(x, rev=true) xy = sum(x .* y) x² = sum(x .* x) y² = sum(y .* y) L_best = score(xy, x², y²) for i in eachindex(x) upper = slopes_perm[begin:i] lower = slopes_perm[i+1:end] upper_set = Set(upper) upper_x = getindex.(Ref(x), upper) upper_y = getindex.(Ref(y .- H), upper) upper_xy = sum(upper_x .* upper_y) upper_x² = sum(upper_x .* upper_x) upper_y² = sum(upper_y .* upper_y) lower_x = getindex.(Ref(x), lower) lower_y = getindex.(Ref(y), lower) lower_xy = sum(lower_x .* lower_y) lower_x² = sum(lower_x .* lower_x) lower_y² = sum(lower_y .* lower_y) L_u = score(upper_xy, upper_x², upper_y²) L_b = score(lower_xy, lower_x², lower_y²) L = L_u + L_b if L < L_best L_best = L end for j in eachindex(x) new_idx = x_perm[j] if new_idx in upper_set upper_xy -= x[new_idx] * (y[new_idx] - H) upper_x² -= x[new_idx]^2 upper_y² -= (y[new_idx] - H)^2 lower_xy += x[new_idx] * y[new_idx] lower_x² += x[new_idx]^2 lower_y² += y[new_idx]^2 else upper_xy += x[new_idx] * (y[new_idx] - H) upper_x² += x[new_idx]^2 upper_y² += (y[new_idx] - H)^2 lower_xy -= x[new_idx] * y[new_idx] lower_x² -= x[new_idx]^2 lower_y² -= y[new_idx]^2 end L_u = score(upper_xy, upper_x², upper_y²) L_b = score(lower_xy, lower_x², lower_y²) L = L_u + L_b if L < L_best L_best = L end end end @printf "%0.20f\n" L_best end main()