#include<bits/stdc++.h>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)

#define ll long long
#define ull unsigned ll

void reader(int *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(ll *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(double *x){scanf("%lf",x);}
int reader(char c[]){int i,s=0;for(;;){mygc(i);if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF) break;}c[s++]=i;for(;;){mygc(i);if(i==' '||i=='\n'||i=='\r'||i=='\t'||i==EOF) break;c[s++]=i;}c[s]='\0';return s;}
template <class T, class S> void reader(T *x, S *y){reader(x);reader(y);}
template <class T, class S, class U> void reader(T *x, S *y, U *z){reader(x);reader(y);reader(z);}
template <class T, class S, class U, class V> void reader(T *x, S *y, U *z, V *w){reader(x);reader(y);reader(z);reader(w);}

void writer(int x, char c){int s=0,m=0;char f[10];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(ll x, char c){int s=0,m=0;char f[20];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(double *x, char c){printf("%.15f",*x);mypc(c);}
void writer(const char c[]){int i;for(i=0;c[i]!='\0';i++)mypc(c[i]);}
void writer(const char x[], char c){int i;for(i=0;x[i]!='\0';i++)mypc(x[i]);mypc(c);}
template<class T> void writerLn(T x){writer(x,'\n');}
template<class T, class S> void writerLn(T x, S y){writer(x,' ');writer(y,'\n');}
template<class T, class S, class U> void writerLn(T x, S y, U z){writer(x,' ');writer(y,' ');writer(z,'\n');}
template<class T> void writerArr(T x[], int n){int i;if(!n){mypc('\n');return;}rep(i,n-1)writer(x[i],' ');writer(x[n-1],'\n');}

char memarr[77000000]; void *mem = memarr;
#define MD 1000000007

double dd(double dx, double dy){ return sqrt(dx*dx+dy*dy); }

int X0, Y0;
int N;
int X[20], Y[20]; double W[20];

double sum[50000];
double dist[20][20];
double dp[50000][20];

int main(){
  int i, j, k, mask;
  double add, res;

  reader(&X0,&Y0);
  reader(&N);
  rep(i,N) reader(X+i,Y+i,W+i), X[i]-=X0, Y[i]-=Y0;

  rep(i,1<<(N+1)){
    sum[i] = 0;
    rep(j,N+1) if(i&1<<j) sum[i] += W[j];
  }

  X[N] = Y[N] = 0;
  rep(i,N+1) rep(j,N+1){
    dist[i][j] = dd(X[i]-X[j], Y[i]-Y[j]);
  }

  N++;
  rep(i,1<<N) rep(j,N) dp[i][j] = 1e100;
  dp[(1<<N)-1][N-1] = 0;
  for(i=(1<<N)-1;i>=0;i--) rep(j,N) if(dp[i][j] < 1e90){
    rep(k,N) if(i&1<<k){
      add = dist[j][k] * (100 + sum[i]) / 120;
      dp[i^(1<<k)][k] = min(dp[i^(1<<k)][k], dp[i][j] + add);
    }
  }

  res = dp[0][N-1];
  res += sum[(1<<N)-1];

  printf("%.15f\n",res);

  return 0;
}