import sys
input = sys.stdin.readline
inf = 1e18


def velocity(w):
    return (w + 100.)/120.


x0, y0 = map(int, input().split())
N = int(input())
M = N + 1
X = [0] * M; Y = [0] * M; W = [0] * M
X[0] = x0
Y[0] = y0
for i in range(1, N + 1):
    x, y, w = input().split()
    X[i] = int(x)
    Y[i] = int(y)
    W[i] = float(w)


dp = [[inf] * M for _ in range(1 << M)]
dp[0][0] = 0
for bit in range(1 << M):
    weight = sum(W[i] for i in range(M) if ~(bit >> i) & 1)
    vel = velocity(weight)
    for s in range(M):
        for t in range(M):
            if ~(bit >> t) & 1:
                bit_next = bit | (1 << t)
                time = vel * (abs(X[s] - X[t]) + abs(Y[s] - Y[t])) + W[t]
                dp[bit_next][t] = min(dp[bit_next][t], dp[bit][s] + time)

print(dp[(1 << M) - 1][0])