def dist(a, b) -> float:
    return abs(a[0] - b[0]) + abs(a[1] - b[1])


def total_weight(mask):
    res = 0
    for i in range(N):
        if mask & (1 << i):
            res += ps[i][1]

    return res


INF = 1 << 60
SX, SY = map(int, input().split())
N = int(input())
ps = []
for _ in range(N):
    a = input().split()
    X, Y, W = int(a[0]), int(a[1]), float(a[2])
    ps.append(((X, Y), W))

dp = [[INF] * N for _ in range(1 << N)]

bit_all = (1 << N) - 1
t = (total_weight(bit_all) + 100) / 120
for i in range(N):
    d = dist((SX, SY), ps[i][0])
    dp[1 << i][i]= d * t + ps[i][1]

for i in range(1 << N):
    for j in range(N):  # 最後に訪問した地点
        if ~i & (1 << j): continue
        if dp[i][j] == INF: continue

        t = (total_weight(~i & bit_all) + 100) / 120
        for k in range(N):  # 次に向かう地点
            if i & (1 << k): continue

            d = dist(ps[j][0], ps[k][0])
            ni = i | (1 << k)
            dp[ni][k] = min(dp[ni][k], dp[i][j] + d * t + ps[k][1])

ans = INF
for i in range(N):
    cost = dp[bit_all][i] + dist(ps[i][0], (SX, SY)) * (100 / 120)
    ans = min(ans, cost)

print(ans)