XY=[]
W=[0]
x0,y0=map(float,input().split())
XY.append((x0,y0))
N=int(input())
S=0
for _ in range(N):
    x,y,w=map(float,input().split())
    XY.append((x,y))
    S+=w
    W.append(w)

MAX=1<<(N+1)
INF=1e18
dp=[[INF for _ in range(N+1)] for _ in range(MAX)]
dp[0][0]=0.0
for s in range(1,MAX):
    for frm in range(N+1):
        if frm!=0 and s&(1<<frm)==0:continue
        for to in range(N+1):
            if s&(1<<to)==0:continue
            bs=s^(1<<to)
            w=S
            for i in range(N+1):
                if bs&(1<<i)>0:w-=W[i]
            t=(w+100)/120
            x0,y0=XY[frm]
            x1,y1=XY[to]
            d=abs(x0-x1)+abs(y0-y1)
            t*=d
            dp[s][to]=min(dp[s][to],dp[bs][frm]+t+W[to])
print(dp[-1][0])