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

#define ll          long long

void Init() {
    ios_base::sync_with_stdio(false),
            cin.tie(nullptr),
            cout.tie(nullptr);
#ifdef CLION
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    freopen("error.txt", "w", stderr);
#else
    //  freopen("input.txt", "r", stdin);
#endif
}

vector<pair<int, int> > adj1, adj2;
vector<vector<int> > adj(50 * 50);
vector<int> a(50 * 50, -1);
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};

bool dfs(int u, vector<bool> &vis) {
    if (vis[u]) return false;
    vis[u] = true;
    for (int v: adj[u]) {
        if (a[v] == -1 || dfs(a[v], vis)) {
            a[v] = u;
            return true;
        }
    }
    return false;
}

void Mesh_JOO() {
    int n, m;
    cin >> n >> m;
    vector<vector<char> > grid(n + 1, vector<char>(m + 1));
    vector<vector<int> > g(n + 1, vector<int>(m + 1));
    int id = 1;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> grid[i][j];
            if (grid[i][j] == 'W')
                adj1.push_back({i, j});
            else if (grid[i][j] == 'G') {
                adj2.push_back({i, j});
                g[i][j] = id++;
            }
        }
    }
    id = 1;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            if (grid[i][j] == 'W') {
                for (int d = 0; d < 4; ++d) {
                    int x = i + dx[d], y = j + dy[d];
                    if (x >= 0 && x < n && y >= 0 && y < m && grid[x][y] == 'G') {
                        adj[id].push_back(g[x][y]);
                    }
                }
                id += 1;
            }
        }
    }
    int ans = 0;
    for (int i = 1; i < id; ++i) {
        vector<bool> vis(50 * 50);
        ans += dfs(i, vis);
    }
    cout << ans << '\n';
}

int main() {
    Init();
    int t{1};
    // cin >> t;
    while (t--) {
        Mesh_JOO();
    }
    return 0;
}