#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <queue>

#include <iostream>

#include <vector>

#include <algorithm>

#define inf 0x3f3f3f3f

using namespace std;

typedef long long ll;

const int INF = 0x3f3f3f3f;

const int maxn = 1e5+;

struct edge

{

    int u, v, c, f, cost;

    edge(int u, int v, int c, int f, int cost) :u(u), v(v), c(c), f(f), cost(cost) {}

};

vector<edge>e;

vector<int>G[maxn];

int a[maxn];//找增广路每个点的水流量

int p[maxn];//每次找增广路反向记录路径

int d[maxn];//SPFA算法的最短路

int inq[maxn];//SPFA算法是否在队列中

void init(int n)

{

    for (int i = ; i <= n; i++)G[i].clear();

    e.clear();

}

void addedge(int u, int v, int c, int cost)

{

    e.push_back(edge(u, v, c, , cost));

    e.push_back(edge(v, u, , , -cost));

    int m = e.size();

    G[u].push_back(m - );

    G[v].push_back(m - );

}

bool bellman(int s, int t, int& flow, long long & cost)

{

    memset(d, inf, sizeof(d));

    memset(inq, , sizeof(inq));

    d[s] = ; inq[s] = ;//源点s的距离设为0，标记入队

    p[s] = ; a[s] = INF;//源点流量为INF（和之前的最大流算法是一样的）

    queue<int>q;//Bellman算法和增广路算法同步进行，沿着最短路拓展增广路，得出的解一定是最小费用最大流

    q.push(s);

    while (!q.empty())

    {

        int u = q.front();

        q.pop();

        inq[u] = ;//入队列标记删除

        for (int i = ; i < G[u].size(); i++)

        {

            edge & now = e[G[u][i]];

            int v = now.v;

            if (now.c > now.f && d[v] > d[u] + now.cost)

                //now.c > now.f表示这条路还未流满（和最大流一样）

                //d[v] > d[u] + e.cost Bellman 算法中边的松弛

            {

                d[v] = d[u] + now.cost;//Bellman 算法边的松弛

                p[v] = G[u][i];//反向记录边的编号

                a[v] = min(a[u], now.c - now.f);//到达v点的水量取决于边剩余的容量和u点的水量

                if (!inq[v]) { q.push(v); inq[v] = ; }//Bellman 算法入队

            }

        }

    }

    if (d[t] == INF)return false;//找不到增广路

    flow += a[t];//最大流的值，此函数引用flow这个值，最后可以直接求出flow

    cost += (long long)d[t] * (long long)a[t];//距离乘上到达汇点的流量就是费用

    for (int u = t; u != s; u = e[p[u]].u)//逆向存边

    {

        e[p[u]].f += a[t];//正向边加上流量

        e[p[u] ^ ].f -= a[t];//反向边减去流量 （和增广路算法一样）

    }

    return true;

}

int MincostMaxflow(int s, int t, long long & cost)

{

    cost = ;

    int flow = ;

    while (bellman(s, t, flow, cost));//由于Bellman函数用的是引用，所以只要一直调用就可以求出flow和cost

    return flow;//返回最大流，cost引用可以直接返回最小费用

}

char mp[][];

int pos[][];

int main()

{

    int n, m, k, cnt = ;

    scanf("%d %d %d", &n, &m, &k);

    for (int i = ; i <= n; i++)

    {

        scanf("%s", mp[i] + );

        for (int j = ; j <= m; j++)

        {

            if (mp[i][j] == '')

            {

                pos[++cnt][] = i;

                pos[cnt][] = j;

            }

        }

    }

    int sum = n + m + k;

    int s = , t = k + cnt * sum + ;

    for (int i = ; i <= cnt; i++)

    {

        for (int j = ; j <= sum; j++)

        {

            int tmp = k + (i - )*sum + j;

            addedge(tmp, t, , );

            if (j != sum) addedge(tmp, tmp + , inf, );

        }

    }

    for (int i = ; i <= k; i++)

    {

        int x, y, w;

        scanf("%d%d%d", &x, &y, &w);

        addedge(s, i, , );

        for (int j = ; j <= cnt; j++)

        {

            int dis = abs(pos[j][] - x) + abs(pos[j][] - y);

            addedge(i, k + (j - )*sum + dis, , dis);

        }

    }

    ll cost = ;

    int ans = MincostMaxflow(s, t, cost);

    printf("%lld\n", cost);

    return ;

}