#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < (n); ++i)
#define all(x) (x).begin(),(x).end()
#define ln '\n'
constexpr long long MOD = 1000000007LL;
//constexpr long long MOD = 998244353LL;
typedef long long ll;
typedef unsigned long long ull; 
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
template<class T, class U> inline bool chmax(T &a, U b) { if (a < b) { a = b; return true;} return false; }
template<class T, class U> inline bool chmin(T &a, U b) { if (a > b) { a = b; return true;} return false; }
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

double dp[5000][15];

double dist(int x1, int y1, int x2, int y2) {return abs(x1-x2)+abs(y1-y2);}

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int X0,Y0; cin >> X0 >> Y0;
    int N; cin >> N;
    vector<double> X(N),Y(N),W(N);
    rep(i,N) cin >> X[i] >> Y[i] >> W[i];

    rep(mask,1<<N) rep(j,N) dp[mask][j] = 1e9;
    rep(mask,1<<N) {
        int S = 0;
        rep(i,N) {
            if (!(mask&(1<<i))) S += W[i];
        }
        if (!mask) {
            rep(i,N) {
                chmin(dp[mask+(1<<i)][i],dist(X0,Y0,X[i],Y[i])*(S+100)/120.0+W[i]); 
            }
        } else {
            rep(i,N) {
                if (mask&(1<<i)) continue;
                rep(j,N) {
                    if (mask&(1<<j)) {
                        chmin(dp[mask+(1<<i)][i],dp[mask][j]+dist(X[i],Y[i],X[j],Y[j])*(S+100)/120.0+W[i]);
                    }
                }
            }
        }
    }

    double ans = 1e9;
    rep(i,N) chmin(ans, dp[(1<<N)-1][i] + 100.0*dist(X0,Y0,X[i],Y[i])/120);

    cout << fixed << setprecision(10) << ans << ln;
}