#include <bits/stdc++.h>
using namespace std;
const long long MOD = 998244353;
int main(){
  int H, W, K;
  cin >> H >> W >> K;
  vector<vector<char>> C(H, vector<char>(W));
  for (int i = 0; i < H; i++){
    for (int j = 0; j < W; j++){
      cin >> C[i][j];
    }
  }
  vector<vector<int>> R(H + W - 1);
  for (int i = 0; i < H; i++){
    for (int j = 0; j < W; j++){
      R[i + j].push_back(i);
    }
  }
  vector<vector<long long>> dp(H, vector<long long>(W, 0));
  vector<vector<long long>> tmp(H, vector<long long>(W, 0));
  vector<vector<long long>> sum1(H + 1, vector<long long>(W, 0));
  vector<vector<long long>> sum2(H, vector<long long>(W + 1, 0));
  vector<vector<long long>> sum(H + W - 1);
  dp[0][0] = 1;
  sum1[1][0] = 1;
  sum2[0][1] = 1;
  sum[0] = {0, 1};
  for (int i = 1; i < H + W - 1; i++){
    int cnt = R[i].size();
    sum[i].resize(cnt + 1);
    sum[i][0] = 0;
    for (int j = 0; j < cnt; j++){
      int r = R[i][j], c = i - r;
      if (r > 0){
        tmp[r][c] = tmp[r - 1][c] + dp[r - 1][c];
        tmp[r][c] += sum2[r][c] - sum2[r][max(c - K, 0)];
        if (i > K){
          int p1 = lower_bound(R[i - K - 1].begin(), R[i - K - 1].end(), max(r - K - 1, 0)) - R[i - K - 1].begin();
          int p2 = lower_bound(R[i - K - 1].begin(), R[i - K - 1].end(), r) - R[i - K - 1].begin();
          tmp[r][c] -= sum[i - K - 1][p2] - sum[i - K - 1][p1];
        }
      } else {
        tmp[r][c] = tmp[r][c - 1] + dp[r][c - 1];
        tmp[r][c] += sum1[r][c] - sum1[max(r - K, 0)][c];
        if (i > K){
          int p1 = lower_bound(R[i - K - 1].begin(), R[i - K - 1].end(), max(r - K, 0)) - R[i - K - 1].begin();
          int p2 = lower_bound(R[i - K - 1].begin(), R[i - K - 1].end(), r + 1) - R[i - K - 1].begin();
          tmp[r][c] -= sum[i - K - 1][p2] - sum[i - K - 1][p1];
        }
      }
      tmp[r][c] %= MOD;
      if (tmp[r][c] < 0){
        tmp[r][c] += MOD;
      }
      if (C[r][c] == '.'){
        dp[r][c] = tmp[r][c];
      }
      sum1[r + 1][c] = (sum1[r][c] + dp[r][c]) % MOD;
      sum2[r][c + 1] = (sum2[r][c] + dp[r][c]) % MOD;
      sum[i][j + 1] = (sum[i][j] + dp[r][c]) % MOD;
    }
  }
  cout << dp[H - 1][W - 1] << endl;
}