#include <bits/stdc++.h>
using namespace std;

typedef long long   signed int LL;
typedef long long unsigned int LU;

#define incID(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define  inc(i, n) incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define  dec(i, n) decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)

#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))

#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define UB upper_bound
#define LB lower_bound
#define PQ priority_queue

#define  ALL(v)  v.begin(),  v.end()
#define RALL(v) v.rbegin(), v.rend()
#define  FOR(it, v) for(auto it =  v.begin(); it !=  v.end(); ++it)
#define RFOR(it, v) for(auto it = v.rbegin(); it != v.rend(); ++it)

template<typename T> bool   setmin(T & a, T b) { if(b <  a) { a = b; return true; } else { return false; } }
template<typename T> bool   setmax(T & a, T b) { if(b >  a) { a = b; return true; } else { return false; } }
template<typename T> bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } }
template<typename T> bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// ---- ----

int n, x[14], y[14];
double w[14], W, dp[1 << 14][14];

int main() {
	cin >> x[0] >> y[0] >> n;
	inc1(i, n) { cin >> x[i] >> y[i] >> w[i]; }
	
	n++;
	
	inc(bit, 1 << n) {
	inc(p, n) {
		dp[bit][p] = 1e6;
	}
	}
	dp[1][0] = 0.0;
	inc(bit, 1 << n) {
	inc(p, n) {
		if((bit >> p) % 2 == 0) { continue; }
		double wr = 0.0;
		inc(i, n) { if((bit >> i) % 2 == 0) { wr += w[i]; } }
		inc(i, n) {
			if((bit >> i) % 2 != 0) { continue; }
			double d = abs(x[p] - x[i]) + abs(y[p] - y[i]);
			double t = d * (wr + 100.0) / 120.0;
			setmin(dp[bit | (1 << i)][i], dp[bit][p] + t);
		}
	}
	}
	double ans = 1e6;
	inc(p, n) {
		int i = 0;
		double d = abs(x[p] - x[i]) + abs(y[p] - y[i]);
		double t = d * (0.0 + 100.0) / 120.0;
		setmin(ans, dp[(1 << n) - 1][p] + t);
	}
	inc(i, n) { ans += w[i]; }
	
	printf("%.9f\n", ans);
	
	return 0;
}