#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define maxs(x,y) (x = max(x,y))
#define mins(x,y) (x = min(x,y))
#define limit(x,l,r) max(l,min(x,r))
#define lims(x,l,r) (x = max(l,min(x,r)))
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)),x.end())
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define show(x) cout<<#x<<" = "<<x<<endl;
#define PQ(T) priority_queue<T,v(T),greater<T> >
#define bn(x) ((1<<x)-1)
#define dup(x,y) (((x)+(y)-1)/(y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef tuple<int,int,int> T;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
typedef vector<T> vt;
inline int in() { int x; scanf("%d",&x); return x;}
template<typename T>inline istream& operator>>(istream&i,v(T)&v)
{rep(j,sz(v))i>>v[j];return i;}
template<typename T>string join(const v(T)&v)
{stringstream s;rep(i,sz(v))s<<' '<<v[i];return s.str().substr(1);}
template<typename T>inline ostream& operator<<(ostream&o,const v(T)&v)
{if(sz(v))o<<join(v);return o;}
template<typename T1,typename T2>inline istream& operator>>(istream&i,pair<T1,T2>&v)
{return i>>v.fi>>v.se;}
template<typename T1,typename T2>inline ostream& operator<<(ostream&o,const pair<T1,T2>&v)
{return o<<v.fi<<","<<v.se;}
template<typename T>inline ll suma(const v(T)& a) { ll res(0); for (auto&& x : a) res += x; return res;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#define dame { puts("0 1"); return 0;}
#define yn {puts("Yes");}else{puts("No");}
const int MX = 200005;

// Fraction
struct frac {
  ll a, b;
  frac(ll a=0, ll b=1){
    ll g = gcd(abs(a),abs(b));
    if (b < 0) g = -g;
    this->a = a/g;
    this->b = b/g;
  }
  ll gcd(ll x, ll y) { return y?gcd(y,x%y):x;}
  // frac inv() const { return frac(b,a);}
  frac operator+(const frac& x) const { return frac(a*x.b + x.a*b, b*x.b);}
  frac operator-(const frac& x) const { return frac(a*x.b - x.a*b, b*x.b);}
  frac operator*(const frac& x) const { return frac(a*x.a, b*x.b);}
  frac operator/(const frac& x) const { return frac(a*x.b, b*x.a);}
  frac& operator+=(const frac& x) { return *this = *this + x;}
  frac& operator-=(const frac& x) { return *this = *this - x;}
  frac& operator*=(const frac& x) { return *this = *this * x;}
  frac& operator/=(const frac& x) { return *this = *this / x;}
  bool operator<(const frac& x) const { return a*x.b < x.a*b;}
};
istream& operator>>(istream&i,frac&a){i>>a.a>>a.b;return i;}
ostream& operator<<(ostream&o,const frac&a){o<<a.a<<" "<<a.b;return o;}
//

int main() {
  int n;
  scanf("%d",&n);
  vp p(n);
  cin>>p;
  vi a;
  rep(i,n) a.pb(max(p[i].fi,p[i].se));
  ll tot = 0;
  rep(i,n) tot += p[i].fi;
  sort(rrng(a));
  vl s(n+1);
  rep(i,n) s[i+1] = s[i]+a[i];

  frac ans;
  rep(i,n) {
    int na = max(p[i].fi,p[i].se);
    int ni = lower_bound(rng(s),tot-p[i].se)-s.begin();
    ll nw = tot-s[ni]; int c = ni;
    if (ni && a[ni-1] <= na) {
      ni = lower_bound(rng(s),tot-p[i].se+na)-s.begin();
      nw = tot+na-s[ni];
      c = ni-1;
    }
    if (nw < 0) continue;
    frac now = frac(n-c) - frac(nw,p[i].se);
    if (ans < now) ans = now;
  }

  ans /= n;
  cout<<ans<<endl;
  return 0;
}




















