#include <iostream>
#include <vector>
#include <string>
#include <queue>
#include <utility>
#include <algorithm>
using namespace std;
void solve(void) {
int n, m, k;
cin >> n >> m >> k;
vector<vector<int> > a(n, vector<int>(m));
for (int i=0; i<n; i++) {
string s;
cin >> s;
for (int j=0; j<m; j++) {
a[i][j] = s[j] - '0';
}
}
vector<vector<vector<int> > > dp(n, vector<vector<int> >(m, vector<int>(k+1, 1e9)));
dp[0][0][0] = 1;
queue<pair<pair<int, int>, int> > q;
q.push(make_pair(make_pair(0, 0), 0));
while (!q.empty()) {
int x = q.front().first.first, y = q.front().first.second, z = q.front().second;
q.pop();
if (x > 0) {
if (a[x-1][y] == 0 && dp[x-1][y][z] > dp[x][y][z] + 1) {
dp[x-1][y][z] = dp[x][y][z] + 1;
q.push(make_pair(make_pair(x-1, y), z));
}
if (a[x-1][y] == 1 && z < k && dp[x-1][y][z+1] > dp[x][y][z] + 1) {
dp[x-1][y][z+1] = dp[x][y][z] + 1;
q.push(make_pair(make_pair(x-1, y), z+1));
}
}
if (x < n-1) {
if (a[x+1][y] == 0 && dp[x+1][y][z] > dp[x][y][z] + 1) {
dp[x+1][y][z] = dp[x][y][z] + 1;
q.push(make_pair(make_pair(x+1, y), z));
}
if (a[x+1][y] == 1 && z < k && dp[x+1][y][z+1] > dp[x][y][z] + 1) {
dp[x+1][y][z+1] = dp[x][y][z] + 1;
q.push(make_pair(make_pair(x+1, y), z+1));
}
}
if (y > 0) {
if (a[x][y-1] == 0 && dp[x][y-1][z] > dp[x][y][z] + 1) {
dp[x][y-1][z] = dp[x][y][z] + 1;
q.push(make_pair(make_pair(x, y-1), z));
}
if (a[x][y-1] == 1 && z < k && dp[x][y-1][z+1] > dp[x][y][z] + 1) {
dp[x][y-1][z+1] = dp[x][y][z] + 1;
q.push(make_pair(make_pair(x, y-1), z+1));
}
}
if (y < m-1) {
if (a[x][y+1] == 0 && dp[x][y+1][z] > dp[x][y][z] + 1) {
dp[x][y+1][z] = dp[x][y][z] + 1;
q.push(make_pair(make_pair(x, y+1), z));
}
if (a[x][y+1] == 1 && z < k && dp[x][y+1][z+1] > dp[x][y][z] + 1) {
dp[x][y+1][z+1] = dp[x][y][z] + 1;
q.push(make_pair(make_pair(x, y+1), z+1));
}
}
}
int ans = 1e9;
for (int i=0; i<=k; i++) {
ans = min(ans, dp[n-1][m-1][i]);
}
cout << (ans == 1e9 ? -1 : ans);
}
int main(void) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}