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

using namespace std;

int n, k;
double x[111], y[111];
double val[111][111];
double opt[111][111];

double getY(int p, int q) {
	//cout << p <<" "<< q <<" "  << -(y[p] - y[p - 1]) / (x[p] - x[p - 1]) * x[q] - y[q] <<endl;
	return (y[p] - y[p - 1]) / (x[p] - x[p - 1]) * (x[q]-x[p])+y[p] - y[q];
}

double calc(int i, int j) {
	double ret = 0;
	for (int k = i; k < j; k++) {
		if ((i > 0 && i < n)&&(j > 0 && j < n)) ret=max(ret,min(getY(i,k),getY(j,k)));
		else if (i > 0 && i < n)
			ret = max(ret, getY(i, k));
		else if (j > 0 && j < n)
			ret = max(ret, getY(j, k));
		//cout <<  ret <<endl;
	}
	//cout << i <<" " << j << " "<< ret <<endl;
	return ret;
}

int main() {
	while (cin >> n >> k) {
		if(!n&&!k) break;
		k++;
		for (int i = 0; i < n; i++)
			scanf("%lf%lf", &x[i], &y[i]);
		for (int i = 0; i <= n; i++)
			for (int j = i + 1; j <= n; j++)
				val[i][j] = calc(i, j);
		for (int i = 0; i <= n; i++)
					for (int j = 0; j <= k; j++) opt[i][j]=1e10;
		opt[0][0] = 0;
		for (int i = 0; i <= n; i++)
			for (int j = 0; j <= k; j++)
				for (int p = i + 1; p <= n; p++) {
					if (i==0&&p==n) continue;
					opt[p][j + 1] = min(opt[p][j + 1],max(opt[i][j], val[i][p]));
				}
		//for (int i = 0; i <= n; i++){
		//			for (int j = 0; j <= k; j++)
		//		cout << opt[i][j] <<" ";
		//	puts("");
		//}
		printf("%.3lf\n",opt[n][k]);
	}
}
/*
 6 2
0.0 0.0
1.0 3.0
3.0 6.0
6.0 9.0
8.0 10.0
17.0 12.0
0 0

 */