n, k = io.read('n'), io.read('n')
x, y = {}, {}
for i = 1, n do x[i], y[i] = io.read('n'), io.read('n') end

ans = 1 << 62

for l = 1, n do
    for r = 1, n do if x[r] > x[l] then
        for u = 1, n do
            for d = 1, n do if y[u] > y[d] then
                local count = 0
                for i = 1, n do
                    if x[i] >= x[l] and x[i] <= x[r] and
                        y[i] >= y[d] and y[i] <= y[u]
                    then
                        count = count + 1
                    end
                end
                if count >= k then
                    ans = math.min(ans, (x[r] - x[l]) * (y[u] - y[d]))
                end
            end end
        end
    end end
end

print(ans)
