tj

#include <iostream>
#include <vector>
#include <cstring>

using namespace std;

const int MAXN = 1005;
int dp[MAXN][MAXN];
char grid[MAXN][MAXN];

int main() {
int n, m;
cin >> n >> m;

for (int i = 0; i < n; ++i) {
    cin >> grid[i];
}
if (grid[0][0] == 'X') {
    cout << 0 << endl;
    return 0;
}
dp[0][0] = 1;
for (int j = 1; j < m; ++j) {
    if (grid[0][j] == 'X') {
        dp[0][j] = 0;
        break;
    } else {
        dp[0][j] = 1;
    }
}

for (int i = 1; i < n; ++i) {
    if (grid[i][0] == 'X') {
        dp[i][0] = 0;
        break; 
    } else {
        dp[i][0] = 1;
    }
}
for (int i = 1; i < n; ++i) {
    for (int j = 1; j < m; ++j) {
        if (grid[i][j] == 'X') {
            dp[i][j] = 0;
        } else {
            dp[i][j] = dp[i-1][j] + dp[i][j-1];
        }
    }
}
cout << dp[n-1][m-1] << endl;

return 0;

}