x,y = map(int,input().split())
n = int(input())+1
N = 1<<n
X = [0]*n
Y = [0]*n
W = [0]*N
X[0],Y[0] = x,y
for i in range(1,n):
    X[i],Y[i],w = map(int,input().split())
    for j in range(1<<i):
        W[j+(1<<i)] = W[j] + w

def d(i,j,w):
    return (abs(X[i]-X[j])+abs(Y[i]-Y[j]))/120*(w+100)

INF = 1e9
dp = [[INF]*n for _ in range(N)] # 残り配達、最後の地点
dp[N-1][0] = 0.0
for mask in range(N-1,-1,-1):
    for i in range(n):
        for j in range(n):
            if i==j: continue
            if mask>>j&1 == 0: continue
            nmask = mask^(1<<j)
            dp[nmask][j] = min(dp[nmask][j],dp[mask][i] + d(i,j,W[mask]) + W[mask]-W[nmask])
print(dp[0][0])