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