#include <bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 998244353;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}

int main() {
  int H, W, K;
  cin >> H >> W >> K;
  auto S = make_v< string >(H);
  cin >> S;

  vector< pair< int, int > > beet;
  int s = 0, t = 0;
  for(int i = 0; i < H; i++) {
    for(int j = 0; j < W; j++) {
      if(S[i][j] != '#' && S[i][j] != '.') {
        if(S[i][j] == 's') continue;
        if(S[i][j] == 'e') continue;
        beet.emplace_back(i, j);
      }
    }
  }


  for(int i = 0; i < H; i++) {
    for(int j = 0; j < W; j++) {
      if(S[i][j] == 's') {
        s = beet.size();
        beet.emplace_back(i, j);
      }
    }
  }
  for(int i = 0; i < H; i++) {
    for(int j = 0; j < W; j++) {
      if(S[i][j] == 'e') {
        t = beet.size();
        beet.emplace_back(i, j);
      }
    }
  }

  const int vy[] = {-1, 0, 1, 0};
  const int vx[] = {0, 1, 0, -1};

  auto mat = make_v< int >(beet.size(), beet.size());
  fill_v(mat, inf);

  int x = 0;
  for(auto &p : beet) {
    queue< pair< int, int > > que;
    que.emplace(p.first, p.second);
    auto d = make_v< int >(H, W);
    fill_v(d, -1);
    d[p.first][p.second] = 0;
    while(que.size()) {
      auto p = que.front();
      que.pop();
      for(int i = 0; i < 4; i++) {
        int ny = p.first + vy[i];
        int nx = p.second + vx[i];
        if(ny < 0 || nx < 0 || ny >= H || nx >= W) continue;
        if(S[ny][nx] == '#') continue;
        if(d[ny][nx] == -1) {
          d[ny][nx] = d[p.first][p.second] + 1;
          que.emplace(ny, nx);
        }
      }
    }
    int y = 0;
    for(auto &q : beet) {
      if(d[q.first][q.second] != -1) {
        mat[x][y] = d[q.first][q.second];
      }
      y++;
    }
    x++;
  }
  auto dp = make_v< int >(1 << (beet.size() - 2), beet.size());
  fill_v(dp, -1);
  auto rec = MFP([&](auto rec, int bit, int cur) -> int {
    if(~dp[bit][cur]) return dp[bit][cur];
    if(__builtin_popcount(bit) >= K) return dp[bit][cur] = mat[cur][t];
    int ret = inf;
    for(int i = 0; i + 2 < beet.size(); i++) {
      if((bit >> i) & 1) continue;
      chmin(ret, rec(bit | (1 << i), i) + mat[cur][i]);
    }
    return dp[bit][cur] = ret;
  });
  auto ret = rec(0, s);
  if(ret >= inf) ret = -1;
  cout << ret << endl;
}



Measured memory_bytes: 126880