n,k = map(int,input().split()) a = [list(map(int,input().split())) for i in range(n)] dp = [[[10**18 for h in range(k+1)] for i in range(n)] for j in range(1<<n)] import math def dist(a,b,c,d): return math.sqrt((a-c)**2 + (b-d)**2) for i in range(n): dp[1<<i][i][k-1] = dist(a[i][0],a[i][1],0,0) for s in range(1<<n): for i in range(n): if(s >> i) & 1 == 0: continue for j in range(n): if(s >> j) & 1 == 1: continue for l in range(k+1): if l != 0: dp[s+(1<<j)][j][l-1] = min(dp[s+(1<<j)][j][l-1],dp[s][i][l] + dist(a[i][0],a[i][1],a[j][0],a[j][1])) dp[s+(1<<j)][j][k-1] = min(dp[s+(1<<j)][j][k-1],dp[s][i][l] + dist(a[i][0],a[i][1],0,0) + dist(0,0,a[j][0],a[j][1])) ans = 10**18 for i in range(n): for j in range(k+1): ans = min(ans,dp[(1<<n)-1][i][j]+dist(0,0,a[i][0],a[i][1])) print(ans)