#include<bits/stdc++.h>
#define fi first
#define se second
#define eb emplace_back
#define mp make_pair
using namespace std;
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
template<typename T,typename U> T ceil(T x, U y) {return (x>0?(x+y-1)/y:x/y);}
template<typename T,typename U> T floor(T x, U y) {return (x>0?x/y:(x-y+1)/y);}
template<class T,class S> bool chmax(T &a,const S b) {return (a<b?a=b,1:0);}
template<class T,class S> bool chmin(T &a,const S b) {return (a>b?a=b,1:0);}
int popcnt(int x) {return __builtin_popcount(x);}
int popcnt(ll x)  {return __builtin_popcountll(x);}
int topbit(int x) {return (x==0?-1:31-__builtin_clz(x));}
int topbit(ll x)  {return (x==0?-1:63-__builtin_clzll(x));}
int lowbit(int x) {return (x==0?-1:__builtin_ctz(x));}
int lowbit(ll x)  {return (x==0?-1:__builtin_ctzll(x));}
 
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
typedef pair<int,int> pii; 
typedef vector<int> vi;
typedef vector<pii> vp;
int read() {
  int x=0,w=1; char c=getchar(); 
  while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
  while(isdigit(c)) {x=x*10+(c-'0'); c=getchar();}
  return x*w;
}

const int N=505;
const double inf=2e9;
int e[N][N],n,m,p[N],t[N],tot;
vi a[N];
double f[N][N],ans;

void dfs(int x,vi y,int pos) {
  if(pos==m) {a[++tot]=y; return;}
  rep(i,x+1,12) {
    vi s=y; s.eb(i);
    dfs(i,s,pos+1);
  }
}

signed main() {
  n=read(), m=read();
  rep(i,1,n) t[i]=read(), p[i]=read();
  vi y; dfs(0,y,0);
  rep(i,1,tot) rep(j,1,tot) {
    rep(k,0,m-1) e[i][j]+=(a[i][k]!=a[j][k]);
  }
  rep(i,1,tot) f[0][i]=inf;
  rep(i,1,n) {
    rep(j,1,tot) {
      f[i][j]=0;
      bool flag=0; double d=t[i]-t[i-1];
      rep(k,0,m-1) flag|=(a[j][k]==p[i]);
      if(flag) {
        rep(k,1,tot) chmax(f[i][j],min(f[i-1][k],d/e[j][k]));
      }
      if(i==n) chmax(ans,f[i][j]);
    }
  }
  if(ans==inf) puts("0.00");
  else printf("%.2lf\n",ans);
  return 0;
}