import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

public class Main {

	static int N, M, K, ans=-1;
	static char[][] map;
	static int[] dr = {-1,0,1,0};
	static int[] dc = {0,1,0,-1};
	
	private static class Pos {
		int r,c,k,move;
		public Pos(int r, int c, int k, int move) {
			super();
			this.r = r;
			this.c = c;
			this.k = k;
			this.move = move;
		}
	}
	
	public static void main(String[] args) throws NumberFormatException, IOException {
		// 1. 입력 및 초기화
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(in.readLine(), " ");
		N = Integer.parseInt(st.nextToken()); // 행
		M = Integer.parseInt(st.nextToken()); // 열
		K = Integer.parseInt(st.nextToken()); // 벽 부술 수 있는 갯수
		map = new char[N][M];
		for(int i=0; i<N; i++) map[i] = in.readLine().toCharArray();
		
		// 2. bfs
		bfs(0, 0);
		
		// 3. 정답 출력
		System.out.println(ans);
	}
	
	public static void bfs(int sr, int sc) {
		Queue<Pos> que = new LinkedList<Pos>();
		boolean[][][] visited = new boolean[K+1][N][M];
		que.offer(new Pos(sr, sc, 0, 1));
		visited[0][sr][sc] = true;
		
		while(!que.isEmpty()) {
			Pos p = que.poll();
			int r = p.r;
			int c = p.c;
			int k = p.k;
			int move = p.move;
			
			if(r == N-1 && c == M-1) {
				ans = move;
				break;
			} // 탈출 성공
			
			int nr, nc;
			for(int d=0; d<4; d++) {
				nr = r + dr[d];
				nc = c + dc[d];
				if(nr > -1 && nr < N && nc > -1 && nc < M) {
					
					// 1) 길인 경우
					if(!visited[k][nr][nc] && map[nr][nc] == '0') {
						visited[k][nr][nc] = true;
						que.offer(new Pos(nr, nc, k, move+1));
					} 
					
					// 2) 벽인 경우
					else if(k+1 <= K && !visited[k+1][nr][nc] && map[nr][nc] == '1') {
						visited[k+1][nr][nc] = true;
						que.offer(new Pos(nr, nc, k+1, move+1));
					}
				}
			}
		}
		
	}
}