#include<bits/stdc++.h> using namespace std; typedef long long int ll; typedef pair<int, int> pii; typedef vector<int> vi; typedef vector<pair<int, int> > vii; #define rrep(i, m, n) for(int (i)=(m); (i)<(n); (i)++) #define erep(i, m, n) for(int (i)=(m); (i)<=(n); (i)++) #define rep(i, n) for(int (i)=0; (i)<(n); (i)++) #define rev(i, n) for(int (i)=(n)-1; (i)>=0; (i)--) #define vrep(i, c) for(__typeof((c).begin())i=(c).begin(); i!=(c).end(); i++) #define ALL(v) (v).begin(), (v).end() #define mp make_pair #define pb push_back template<class T1, class T2> inline void minup(T1& m, T2 x){ if(m>x) m=static_cast<T2>(x); } template<class T1, class T2> inline void maxup(T1& m, T2 x){ if(m<x) m=static_cast<T2>(x); } #define INF 1000000000.0 #define MOD 1000000007 #define EPS 1E-12 const int MAX_N = 14; int s, t; int x[MAX_N], y[MAX_N]; double w[MAX_N]; double dp[1<<MAX_N][MAX_N]; int n; double cost(int S) { double res = 0.0; rep(i, n) if(!(S & 1 << i)) res += w[i]; return (res + 100) / 120.0; } inline double dist(int i, int j, int S){ return (abs(x[i]-x[j])+abs(y[i]-y[j]))*cost(S); } int main() { cin >> x[0] >> y[0]; cin >> n; n += 1; rrep(i, 1, n) cin >> x[i] >> y[i] >> w[i]; rep(S, 1<<n) rep(v, n) dp[S][v] = INF; dp[0][0] = 0.0; rep(S, 1<<n) rep(v, n) if(dp[S][v] < INF) rep(u, n) if(!(S & 1 << u)) minup(dp[S | 1 << u][u], dp[S][v] + dist(v, u, S) + w[u]); printf("%.10f\n", dp[(1<<n)-1][0]); return 0; }