import sys
readline=sys.stdin.readline
read=sys.stdin.read

x,y=map(int,readline().split())
N=int(readline())
X,Y,W=zip(*[list(map(float,readline().split())) for i in range(N)])
inf=1<<30
dp=[[inf]*N for bit in range(1<<N)]
for i in range(N):
    dp[1<<i][i]=(abs(X[i]-x)+abs(Y[i]-y))*(sum(W)+100)/120
for bit in range(1<<N):
    for i in range(N):
        if bit&1<<i:
            for j in range(N):
                if i==j:
                    continue
                if bit&1<<j:
                    dp[bit][i]=min(dp[bit][i],dp[bit^1<<i][j]+(abs(X[i]-X[j])+abs(Y[i]-Y[j]))*(sum(W[k] for k in range(N) if not bit&1<<k)+W[i]+100)/120)
ans=min(dp[-1][i]+(abs(X[i]-x)+abs(Y[i]-y))*100/120 for i in range(N))+sum(W)
print(ans)