#include <iostream>
#include <vector>
#include <cstdio>

using namespace std;

class UnionFind {
public:
    explicit UnionFind(int N) : root(N, -1), size(N, 1) {}
    int getRoot(int u){ return root[u] == -1 ? u : root[u] = getRoot(root[u]); }
    int getSize(int u){ return size[getRoot(u)]; }
    bool same(int a, int b){
        return getRoot(a) == getRoot(b);
    }
    bool merge(int a, int b){
        int u = getRoot(a);
        int v = getRoot(b);
        if(u == v) return false;
        root[u] = v;
        size[v] += size[u];
        return true;
    }
private:
    vector<int> root;
    vector<int> size;
};

int main(){
    int N; cin >> N;
    vector<int> x(N), y(N);
    for(int i=0;i<N;i++) cin >> x[i] >> y[i];
    double L = 0, R = 100;
    for(int _=0;_<200;_++){
        double mid = 0.5*(L+R);
        UnionFind uf(N+2);
        for(int i=0;i<N;i++){
            if(100-y[i] < 2*mid) uf.merge(i, N);
            if(y[i]+100 < 2*mid) uf.merge(i, N+1);
            for(int j=i+1;j<N;j++){
                int dx = (x[i] - x[j]);
                int dy = (y[i] - y[j]);
                if(dx*dx+dy*dy < 4*mid*mid) uf.merge(i, j);
            }
        }
        if(uf.same(N, N+1)) R = mid;
        else L = mid;
    }
    printf("%.9lf\n", 0.5*(L+R));

}
#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef long double ld;
typedef complex<double> comp;
const ll INF=1e9+7;
const ll inf=INF*INF;
const ll MOD=998244353;
const ll mod=MOD;
const int MAX=100010;


signed main(){
    ll x,y;cin>>x>>y;
    ll a,b;cin>>a>>b;
    ll cnt=0;
    while(a<=(y-1)/x&&x<b&&(a-1)<b&&x*(a-1)<b){
        cnt++;
        x*=a;
    }
    cnt+=max(0LL,(y-x-1)/b);
    cout<<cnt<<endl;
}