X0, Y0 = map(int, input().split())
XY = [(X0, Y0)]
weight = [0]
N = int(input())

for _ in range(N):
    Xi, Yi, Wi = map(float, input().split())
    XY.append((Xi, Yi))
    weight.append(Wi)

dist = [[0]*(N+1) for _ in range(N+1)]

for i in range(N+1):
    Xi, Yi = XY[i]
    
    for j in range(i+1, N+1):
        Xj, Yj = XY[j]
        d = abs(Xi-Xj)+abs(Yi-Yj)
        dist[i][j] = d
        dist[j][i] = d

W = sum(weight)
dp = [[10**18]*(N+1) for _ in range(1<<(N+1))]
dp[0][0] = 0

for S in range(1<<(N+1)):
    w = W
    
    for i in range(N+1):
        if (S>>i)&1:
            w -= weight[i]
    
    t = (100+w)/120
    
    for i in range(N+1):
        if not (S>>i)&1:
            for j in range(N+1):
                dp[S|(1<<i)][i] = min(dp[S|(1<<i)][i], dp[S][j]+t*dist[i][j])

print(dp[-1][0]+W)