//Daniel Grzegorzewski
#include <bits/stdc++.h>

#define MP make_pair
#define PB push_back
#define ST first
#define ND second

using namespace std;

typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VII;

void init_ios()
{
     ios_base::sync_with_stdio(0);
     cin.tie(0);
}

const int INF = (int)1e9;
const int N = (int)1e6 + 10;

int n, m, c;
int res = INF;
int t, id_pyl[N];
bool vis[N], pylek[N], vis_pyl[N], wygrany_pyl[N];
VI dzieci[N];

struct Node
{
    VI child;
    int r;  //1 wolne, 2 - zajete
} w[N];

void jebaj_pylek(int i)
{
    if (pylek[i])
        return;
    pylek[i] = true;
    id_pyl[i] = t;
    if (i >= m*n-m)
        wygrany_pyl[t] = true;
    if (i+m < m*n && w[i+m].r == 1)
        jebaj_pylek(i+m);
    if (i+m < m*n && w[i+m].r == 0)
        dzieci[t].PB(i+m);
    if (i+m-1 < m*n && i%m != 0 && w[i+m-1].r == 1)
        jebaj_pylek(i+m-1);
    if (i+m-1 < m*n && i%m != 0 && w[i+m-1].r == 0)
        dzieci[t].PB(i+m-1);
    if (i >= m && i%m != 0 && w[i-1].r == 1)
        jebaj_pylek(i-1);
    if (i >= m && i%m != 0 && w[i-1].r == 0)
        dzieci[t].PB(i-1);
    if (i >= m && (i+1)%m != 0 && i+1 < m*n && w[i+1].r == 1)
        jebaj_pylek(i+1);
    if (i >= m && (i+1)%m != 0 && i+1 < m*n && w[i+1].r == 0)
        dzieci[t].PB(i+1);
    if (i >= m && w[i-m].r == 1)
        jebaj_pylek(i-m);
    if (i >= m && w[i-m].r == 0)
        dzieci[t].PB(i-m);
    if (i >= m && (i+1)%m != 0 && w[i-m+1].r == 1)
        jebaj_pylek(i-m+1);
    if (i >= m && (i+1)%m != 0 && w[i-m+1].r == 0)
        dzieci[t].PB(i-m+1);
}

void jebaj(int i)
{
    if (pylek[i])
        return;
    jebaj_pylek(i);
    ++t;
}

queue<PII> q;

int main()
{
    init_ios();
    cin >> m >> n >> c;
    for (int i = 1; i <= c; ++i) {
        int x, y;
        char r;
        cin >> y >> x >> r;
        --x;
        --y;
        if (r == 'o')
            w[m*x+y].r = 1;
        else
            w[m*x+y].r = 2;
    }

    for (int i = 0; i < m*n; ++i) {
        if (w[i].r == 2)
            continue;
        if (w[i].r == 1) {
            jebaj(i);
            continue;
        }
        if (i+m < m*n)
            w[i].child.PB(i+m);
        if (i+m-1 < m*n && i%m != 0)
            w[i].child.PB(i+m-1);
        if (i >= m && i%m != 0)
            w[i].child.PB(i-1);
        if (i >= m && (i+1)%m != 0 && i+1 < m*n)
            w[i].child.PB(i+1);
        if (i >= m)
            w[i].child.PB(i-m);
        if (i >= m && (i+1)%m != 0)
            w[i].child.PB(i-m+1);
    }
    for (int i = 0; i < m; ++i) {
        if (w[i].r == 2)
            continue;
        if (w[i].r == 1) {
            if (wygrany_pyl[id_pyl[i]]) {
                cout<<"0\n";
                return 0;
            }
            for (int j = 0; j < dzieci[id_pyl[i]].size(); ++j) {
                if (vis[dzieci[id_pyl[i]][j]])
                    continue;
                vis[dzieci[id_pyl[i]][j]] = true;
                q.push(MP(dzieci[id_pyl[i]][j], 1));
            }
            vis_pyl[id_pyl[i]] = vis[i] = true;
        }
    }
    for (int i = 0; i < m; ++i)
        if (w[i].r == 0 && !vis[i]) {
            vis[i] = true;
            q.push(MP(i, 1));
        }

    while (!q.empty()) {
        PII x = q.front();
        q.pop();
        if (x.ST >= n*m-m) {
            cout<<x.ND<<"\n";
            return 0;
        }
        for (int i = 0; i < w[x.ST].child.size(); ++i) {
            if (vis[w[x.ST].child[i]])
                continue;
            if (pylek[w[x.ST].child[i]]) {
                if (wygrany_pyl[id_pyl[w[x.ST].child[i]]]) {
                    cout<<x.ND<<"\n";
                    return 0;
                }
                if (vis_pyl[id_pyl[w[x.ST].child[i]]])
                    continue;
                else {
                    vis_pyl[id_pyl[w[x.ST].child[i]]] = true;
                    for (int j = 0; j < dzieci[id_pyl[w[x.ST].child[i]]].size(); ++j) {
                        if (vis[dzieci[id_pyl[w[x.ST].child[i]]][j]])
                            continue;
                        vis[dzieci[id_pyl[w[x.ST].child[i]]][j]] = true;
                        q.push(MP(dzieci[id_pyl[w[x.ST].child[i]]][j], x.ND+1));
                    }
                }
            }
            else {
                vis[w[x.ST].child[i]] = true;
                q.push(MP(w[x.ST].child[i], x.ND+1));
            }
        }
    }
    cout<<"-1\n";
}