#include <cstdio>
#include <algorithm>

double dp[1<<13][14], weight[1<<13];
double X[14], Y[14], W[14];
int N;

double dist(int i, int j){
    return std::abs(X[i] - X[j]) + std::abs(Y[i] - Y[j]);
}

double rec(int state, int index){
    if(state == 0){
        return 100.0 / 120 * dist(0, index);
    }
    if(dp[state][index] > 0.0){return dp[state][index];}

    double res = 1e20;
    for(int i=0;i<N;i++){
        if(!(state >> i & 1)){continue;}

        res = std::min(res, (weight[state] + 100) / 120 * dist(index, i+1) + W[i+1] + rec(state & ~(1 << i), i+1));
    }

    return dp[state][index] = res;
}

int main(){
    scanf("%lf %lf", &X[0], &Y[0]);
    
    scanf("%d", &N);
    
    for(int i=0;i<1<<N;i++){
        for(int j=0;j<=N;j++){
            dp[i][j] = -1.0;
        }
    }

    for(int i=1;i<=N;i++){
        scanf("%lf %lf %lf", X+i, Y+i, W+i);
    }

    for(int i=0;i<1<<N;i++){
        double sum = 0.0;
        for(int j=0;j<N;j++){
            if(!(i >> j & 1)){continue;}
            sum += W[j+1];
        }
        weight[i] = sum;
    }

    printf("%.6f\n", rec((1<<N)-1, 0));
}