def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    X0 = int(input[idx])
    idx += 1
    Y0 = int(input[idx])
    idx += 1
    N = int(input[idx])
    idx += 1
    points = []
    sum_W = 0.0
    for _ in range(N):
        x = int(input[idx])
        idx += 1
        y = int(input[idx])
        idx += 1
        w = float(input[idx])
        idx += 1
        points.append((x, y, w))
        sum_W += w

    # Precompute mask_sum
    mask_sum = [0.0] * (1 << N)
    for mask in range(1 << N):
        s = 0.0
        for j in range(N):
            if mask & (1 << j):
                s += points[j][2]
        mask_sum[mask] = s

    # Precompute distance matrix
    size = N + 1  # 0..N-1: delivery points, N: liquor store
    dist = [[0] * (size) for _ in range(size)]
    for u in range(size):
        x_u = X0 if u == N else points[u][0]
        y_u = Y0 if u == N else points[u][1]
        for v in range(size):
            x_v = X0 if v == N else points[v][0]
            y_v = Y0 if v == N else points[v][1]
            dist[u][v] = abs(x_u - x_v) + abs(y_u - y_v)

    # Initialize DP
    INF = float('inf')
    state_count = 1 << N
    dp = [[INF] * (size) for _ in range(state_count)]
    dp[0][N] = 0.0  # mask 0, at liquor store (u=N), time 0

    for mask in range(state_count):
        for u in range(size):
            current_time = dp[mask][u]
            if current_time == INF:
                continue
            # If all visited, skip (handled later)
            if mask == (1 << N) - 1:
                continue
            # Try visit all unvisited delivery points v (0..N-1)
            for v in range(N):
                if not (mask & (1 << v)):
                    new_mask = mask | (1 << v)
                    current_W = sum_W - mask_sum[mask]
                    d = dist[u][v]
                    moving_time = d * (current_W + 100) / 120
                    unloading_time = points[v][2]
                    total = current_time + moving_time + unloading_time
                    if total < dp[new_mask][v]:
                        dp[new_mask][v] = total

    # After all state transitions, check return to liquor store
    min_total = INF
    full_mask = (1 << N) - 1
    for u in range(N):
        if dp[full_mask][u] == INF:
            continue
        d = dist[u][N]
        return_time = d * (100) / 120
        total = dp[full_mask][u] + return_time
        if total < min_total:
            min_total = total

    print("{0:.9f}".format(min_total))

if __name__ == '__main__':
    main()