#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <functional>

typedef long long int ll;
using namespace std;
#define INF 1234567890
#define N 200000

const int LIMIT = 1e+9;
int n, m, k_limit;

string mmap[1005];
int dist[1005][1005][15];
int dx[4] = { 0, 0, 1, -1 };
int dy[4] = { 1, -1, 0 ,0 };

struct POS {
	int x, y, k;
	POS() {}
	POS(int _x, int _y, int _k) : x(_x), y(_y), k(_k) {}
};


bool is_out_of_range(int x, int y) {
	return x < 0 || x >= n || y < 0 || y >= m;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	cin >> n >> m >> k_limit;
	for (int i = 0; i < n; i++) {
		cin >> mmap[i];
	}

	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			for (int k = 0; k <= k_limit; k++) {
				dist[i][j][k] = -1;
			}
		}
	}

	queue<POS> que;
	que.push(POS(0,0,0));
	dist[0][0][0] = 1;

	while (!que.empty()) {
		
		POS here = que.front();
		que.pop();
		if (here.x == n - 1 && here.y == m - 1) {
			cout << dist[here.x][here.y][here.k];
			return 0;
		}
		for (int i = 0; i < 4; i++) {
			int cx = here.x + dx[i];
			int cy = here.y + dy[i];
			int k = here.k;
			if (is_out_of_range(cx, cy) || dist[cx][cy][k] != -1)
				continue;
			if (mmap[cx][cy] == '1') {
				if (k < k_limit) {
					que.push(POS(cx, cy, k + 1));
					dist[cx][cy][k + 1] = dist[here.x][here.y][here.k] + 1;
				}
				continue;
			}

			que.push(POS(cx, cy, k));
			dist[cx][cy][k] = dist[here.x][here.y][here.k] + 1;
		}
	}
	cout << -1;
	

	return 0;
}