import math
X0,Y0=map(int,raw_input().split())
N=int(raw_input())
D=[map(float,raw_input().split()) for i in range(N)]
dp=[[50000000 for i in range(N)] for j in range(1<<N)]
tot = 0
for i in range(N):
    tot+=D[i][2]

W=[tot for i in range(1<<N)]
for i in range(1<<N):
    for j in range(N):
        if (i&(1<<j))>0:
            W[i]-=D[j][2]
            
for i in range(N):
    dx=abs(X0-D[i][0])
    dy=abs(Y0-D[i][1])
    dp[(1<<i)][i]=(dx+dy)*(100+tot)/120.0

for i in range(1<<N):
    for j in range(N):
        if (i&(1<<j))>0:
            for k in range(N):
                if (i&(1<<k))==0:
                    dx=abs(D[j][0]-D[k][0])
                    dy=abs(D[j][1]-D[k][1])
                    dp[i|1<<k][k]=min(dp[i|1<<k][k],dp[i][j]+(dx+dy)*(100+W[i])/120.0)
#for i in range(1<<N):
#    for j in range(N):
#        print "dp[",i,"][",j,"]=",dp[i][j], " "
#    print 

ans=500000000
for i in range(N):
    dx=abs(X0-D[i][0])
    dy=abs(Y0-D[i][1])
    ans=min(ans,tot+dp[(1<<N)-1][i]+(dx+dy)*100/120.0)

print "%.8f"%ans