#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define pb push_back
#define mp make_pair
#define all(a) begin(a),end(a)
#define FOR(x,val,to) for(int x=(val);x<int((to));++x)
#define FORE(x,val,to) for(auto x=(val);x<=(to);++x)
#define FORR(x,arr) for(auto &x: arr)
#define FORS(x,plus,arr) for(auto x = begin(arr)+(plus); x != end(arr); ++x)
#define FORREV(x,plus,arr) for(auto x = (arr).rbegin()+(plus); x !=(arr).rend(); ++x)
#define REE(s_) {cout<<s_<<'\n';exit(0);}
#define GET(arr) for(auto &i: (arr)) sc(i)
#define whatis(x) cerr << #x << " is " << (x) << endl;
#define e1 first
#define e2 second
#define INF 0x7f7f7f7f
typedef std::pair<int,int> pi;
typedef std::vector<int> vi;
typedef std::vector<std::string> vs;
typedef int64_t ll;
typedef uint64_t ull;
#define umap unordered_map
#define uset unordered_set
using namespace std;
using namespace __gnu_pbds;

#ifdef _WIN32
#define getchar_unlocked() _getchar_nolock()
#define _CRT_DISABLE_PERFCRIT_LOCKS
#endif
template<class L, class R> ostream& operator<<(ostream &os, map<L, R> P) { for(auto const &vv: P)os<<"("<<vv.first<<","<<vv.second<<")"; return os; }
template<class T> ostream& operator<<(ostream &os, set<T> V) { os<<"[";for(auto const &vv:V)os<<vv<<","; os<<"]"; return os; }
template<class T> ostream& operator<<(ostream &os, vector<T> V) { os<<"[";for(auto const &vv:V)os<<vv<<","; os<<"]"; return os; }
template<class L, class R> ostream& operator<<(ostream &os, pair<L, R> P) { os<<"("<<P.first<<","<<P.second<<")"; return os; }
inline int fstoi(const string &str){auto it=str.begin();bool neg=0;int num=0;if(*it=='-')neg=1;else num=*it-'0';++it;while(it<str.end()) num=num*10+(*it++-'0');if(neg)num*=-1;return num;}
inline void getch(char &x){while(x = getchar_unlocked(), x < 33){;}}
inline void getstr(string &str){str.clear(); char cur;while(cur=getchar_unlocked(),cur<33){;}while(cur>32){str+=cur;cur=getchar_unlocked();}}
template<typename T> inline bool sc(T &num){ bool neg=0; int c; num=0; while(c=getchar_unlocked(),c<33){if(c == EOF) return false;} if(c=='-'){ neg=1; c=getchar_unlocked(); } for(;c>47;c=getchar_unlocked()) num=num*10+c-48; if(neg) num*=-1; return true;}template<typename T, typename ...Args> inline void sc(T &num, Args &...args){ bool neg=0; int c; num=0; while(c=getchar_unlocked(),c<33){;} if(c=='-'){ neg=1; c=getchar_unlocked(); } for(;c>47;c=getchar_unlocked()) num=num*10+c-48; if(neg) num*=-1; sc(args...); }
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; //s.find_by_order(), s.order_of_key() <- works like lower_bound
template<typename T> using ordered_map = tree<T, int, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define N 1000001

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    int n;
    int a[1005][3];
    cout << fixed << setprecision(9);
    sc(a[0][0]);
    sc(a[0][1]);
    sc(a[1][0]);
    sc(a[1][1]);
    sc(n);
    n += 2;
    a[0][2] = a[1][2] = 0;
    FOR(i,2,n){
        FORR(x,a[i])
            sc(x);
    }
    double ds[n][n];
    double dist[n];
    FORR(i,ds)
        FORR(x,i)
            x = 4e9;
    FOR(i,0,n){
        FOR(x,0,n){
            ds[i][x] = max(0.0,hypot(a[i][0]-a[x][0],a[i][1]-a[x][1])-a[i][2]-a[x][2]);
        }
    }
    FORR(i,dist) i = 1.0/0.0;
    dist[0] = 0;
    priority_queue<pair<double,int>> pq;
    pq.push({0,0});
    while(!pq.empty()){
        int v = pq.top().e2;
        double w = -pq.top().e1;
        pq.pop();
        /* whatis(v) */
        /* whatis(w) */
        if(dist[v] != w) continue;
        FOR(i,0,n){
            double neww = w + ds[v][i];
            if(neww < dist[i]){
                dist[i] = neww;
                pq.push({-neww,i});
            }
        }
    }
    /* for(int k = 0; k < n; ++k) */
        /* for(int i = 0; i < n; ++i){ */
        /*     for(int j = 0; j < n; ++j) */
        /*         ds[0][j] = min(ds[0][j],ds[0][i]+ds[i][j]); */
        /* } */
    /* cout << ds[0][1] << '\n'; */
    cout << dist[1] << '\n';
}



Measured memory_bytes: 13296