#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001


int main() {
    
	int H,W,K;
	cin>>H>>W>>K;
	
	vector dp(H,vector<mint>(W,0));
	vector sum(H,vector<mint>(W,0));
	
	vector<string> s(H);
	rep(i,H)cin>>s[i];
	
	rep(i,H){
		mint cs = 0;
		if(i!=0)cs += sum[i-1][0];
		if(i-K-1>=0)cs -= sum[i-(K+1)][0];
		rep(j,W){
			mint v = cs;
			if(i==0&&j==0)v++;
			
			if(s[i][j]=='.'){
				dp[i][j] += v;
				sum[i][j] += v;
			}
			else v = 0;
			if(i!=0&&j!=W-1)dp[i][j] += dp[i-1][j+1];
			if(i!=0)sum[i][j] += sum[i-1][j];
			if(j!=W-1){
				cs += v;
				if(j-(K)>=0){
					int y = j-(K);
					int x = i;
					if(y>=0)cs -= dp[x][y];
					x -= (j+1)-y;
					y = j+1;
					if(x>=0 && y<W)cs += dp[x][y];
				}
				else{
					int y = 0;
					int x = i - ((K)-(j));
					if(x>=0)cs -= dp[x][y];
					x -= j+1;
					y += j+1;
					if(x>=0&&y<W)cs += dp[x][y];
				}
				if(i!=0)cs += sum[i-1][j+1];
				if(i-(K+1)>=0)cs -= sum[i-(K+1)][j+1];
			}
				
		}
	}
	
	cout<<dp[H-1][W-1].val()<<endl;
	
    return 0;
}