#include <bits/stdc++.h>
using namespace std;

typedef long double ld;

deque<ld> v;

ld chord(ld a){
  return (a-sinl(a))*0.5L;
}

ld best=0.L;

void go(int x,int rx,int m,ld score){
  if (m==0 or x==rx){
    if (m==0 and x==rx) best=max(best,score);
    return;
  }
  for (int j=x+1; j<=rx+1-m; j++){
    go(j,rx,m-1,score-chord(v[j]-v[x]));
  }
}

int main(){
  int n; cin>>n;
  int m; cin>>m;
  v.resize(n); for (auto &i: v) cin>>i, i*=M_PI/180.L;
  for (int i=0; i<n; i++) v.push_back(v[i]+M_PI*2);
  for (int i=0; i<n; i++){
    go(i,i+n,m,M_PI);
  }

  cout.precision(18);
  cout<<best*1000000<<endl;
}