#include <iostream>
#include <algorithm>
#include <cstdio>

using namespace std;

static const int SIZE = 1024;
static const double MAX = 1e10;

//i番目からj番目まで(inclusive)
double memoMin[SIZE][SIZE];	//最小値
double memoMax[SIZE][SIZE];	//最大値
double memoError[SIZE][SIZE];	//区間二乗誤差
double memoAnswer[SIZE][SIZE];	//解

int main()
{
	int N, M, L;
	while (cin >> N >> M >> L && N && M && L){
		double values[SIZE];
		for (int i = 0; i < N; ++i){
			cin >> values[i];
		}

		fill_n((double*)memoMin, SIZE * SIZE, MAX);
		fill_n((double*)memoMax, SIZE * SIZE, MAX);
		fill_n((double*)memoError, SIZE * SIZE, MAX);
		fill_n((double*)memoAnswer, SIZE * SIZE, MAX);

		//i番目からj番目までの範囲のサンプルの最小値、最大値を求める O(N^2)
		for (int from = 0; from < N; ++from){
			double minValue = values[from];
			double maxValue = values[from];

			for (int to = from + 1; to < N; ++to){
				minValue = min(minValue, values[to]);
				maxValue = max(maxValue, values[to]);

				memoMin[from][to] = minValue;
				memoMax[from][to] = maxValue;
			}
		}

		//i番目からj番目までの範囲のサンプルの二乗量子化誤差の和をDPで求める O(N^3)
		for (int from = 0; from < N; ++from){
			for (int to = from + 1; to < N; ++to){
				const double minValue = memoMin[from][to];
				const double maxValue = memoMax[from][to];
				const double stepSize = (maxValue - minValue) / ((1 << L) - 1);

				double sum2 = 0;

				for (int current = from; current <= to; ++current){
					const double currentValue = values[current];
					const double estimatedValue = (int)((currentValue - minValue + stepSize * 0.5) / stepSize) * stepSize + minValue;
					const double error = currentValue - estimatedValue;
					sum2 += error * error;
				}

				memoError[from][to] = sum2;
			}
		}

		//i番目までにj個の時分割フレームを使用した時の二乗量子化誤差の和をDPで求める O(N^3)
		for (int to = 1; to < N; ++to){
			memoAnswer[1][to] = memoError[0][to];
		}
		for (int numberOfFrames = 2; numberOfFrames <= M; ++numberOfFrames){
			for (int from = 1; from < N; ++from){
				for (int to = from + 1; to < N; ++to){
					double& answer = memoAnswer[numberOfFrames][to];
					answer = min(answer, memoAnswer[numberOfFrames - 1][from - 1] + memoError[from][to]);
				}
			}
		}

		printf("%.20lf\n", memoAnswer[M][N - 1]);
	}
}