import collections

def read_data():
    x0, y0 = map(int, input().split())
    N = int(input())
    XY = [(0, 0)]
    W = [0.0]
    for i in range(N):
        x, y, w = input().split()
        XY.append((int(x) - x0, int(y) - y0))
        W.append(float(w))
    return N, XY, W

def solve(N, XY, W):
    global record
    T, N, XY, W = simplify(N, XY, W)
    dist = [[abs(xi - xj) + abs(yi - yj) for (xj, yj) in XY] for (xi, yi) in XY]
    time = T + wfs(N, W, dist) / 120.0
    return time

def simplify(N, XY, W):
    pos_w = collections.defaultdict(int)
    for (x, y), w in zip(XY, W):
        pos_w[x, y] += w
    newXY = [(0, 0)]
    newW = [0]
    del pos_w[0, 0]
    for (x, y), w in pos_w.items():
        newXY.append((x, y))
        newW.append(w)
    return sum(W), len(newW), newXY, newW

def wfs(N, W, dist):
    frontiers = {(0, 1): (0, sum(W) + 100)}
    for n_used in range(1, N):
        new_frontiers = dict()
        for (pos, used_bits), (cum_t, cum_w) in frontiers.items():
            dpos = dist[pos]
            for new_pos in range(N):
                if (1 << new_pos) & used_bits:
                    continue
                new_cum_t = cum_t + cum_w * dpos[new_pos]
                new_cum_w = cum_w - W[new_pos]
                new_used_bits = used_bits | (1 << new_pos)
                if (new_pos, new_used_bits) in new_frontiers:
                    ct, cw = new_frontiers[new_pos, new_used_bits]
                    if ct > new_cum_t:
                        new_frontiers[new_pos, new_used_bits] = (new_cum_t, new_cum_w)
                else:
                    new_frontiers[new_pos, new_used_bits] = (new_cum_t, new_cum_w)
        frontiers = new_frontiers
    best_t = float('inf')
    for (pos, used_bits), (cum_t, cum_w) in frontiers.items():
        t = cum_t + cum_w * dist[pos][0]
        if t < best_t:
            best_t = t
    return best_t

N, XY, W = read_data()
print(solve(N, XY, W))