#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <limits>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <functional>
#include <iomanip>

using namespace std;

#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define eprintf(...) 42
#endif
using ll = long long;
using vll = std::vector<ll>;
using vvll = std::vector<vll>;
using vvvll = std::vector<vvll>;
#define reps(i, S, E) for (ll i = (S); i <= (E); i++)
#define rep(i, N) reps(i, 0, N-1)
#define deps(i, E, S) for (ll i = (E); i >= (S); i--)
#define dep(i, N) deps(i, N-1, 0)
const ll INF = 1LL << 60;
const int INF_INT = 1 << 30;

template<class T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; }return false; }
template<class T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; }return false; }
struct mll {
	static ll MOD;
	ll val;
	mll(ll v = 0) : val(v % MOD) { if (val < 0) val += MOD; }
	mll operator - () const { return -val; }
	mll operator + (const mll &b) const { return val + b.val; }
	mll operator - (const mll &b) const { return val - b.val; }
	mll operator * (const mll &b) const { return val * b.val; }
	mll operator / (const mll &b) const { return mll(*this) /= b; }
	mll operator + (ll b) const { return *this + mll(b); }
	mll operator - (ll b) const { return *this - mll(b); }
	mll operator * (ll b) const { return *this * mll(b); }
	friend mll operator + (ll a, const mll &b) { return b + a; }
	friend mll operator - (ll a, const mll &b) { return -b + a; }
	friend mll operator * (ll a, const mll &b) { return b * a; }
	mll &operator += (const mll &b) { val = (val + b.val) % MOD; return *this; }
	mll &operator -= (const mll &b) { val = (val + MOD - b.val) % MOD; return *this; }
	mll &operator *= (const mll &b) { val = (val*b.val) % MOD; return *this; }
	mll &operator /= (const mll &b) {
		ll c = b.val, d = MOD, u = 1, v = 0;
		while (d) {
			ll t = c / d;
			c -= t * d; swap(c, d);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	mll &operator += (ll b) { return *this += mll(b); }
	mll &operator -= (ll b) { return *this -= mll(b); }
	mll &operator *= (ll b) { return *this *= mll(b); }
	mll &operator /= (ll b) { return *this /= mll(b); }
	bool operator == (const mll &b) { return val == b.val; }
	bool operator != (const mll &b) { return val != b.val; }
	bool operator == (ll b) { return *this == mll(b); }
	bool operator != (ll b) { return *this != mll(b); }
	friend bool operator == (ll a, const mll &b) { return mll(a) == b.val; }
	friend bool operator != (ll a, const mll &b) { return mll(a) != b.val; }
	friend ostream &operator << (ostream &os, const mll &a) { return os << a.val; }
	friend istream &operator >> (istream &is, mll &a) { return is >> a.val; }
	static mll Combination(ll a, ll b) {
		chmin(b, a - b);
		if (b < 0) return mll(0);
		mll c = 1;
		rep(i, b) c *= a - i;
		rep(i, b) c /= i + 1;
		return c;
	}
};
using vmll = std::vector<mll>;
using vvmll = std::vector<vmll>;
using vvvmll = std::vector<vvmll>;
using vvvvmll = std::vector<vvvmll>;

struct Fast {
	Fast() {
		cin.tie(0);
		ios::sync_with_stdio(false);
		cout << fixed << setprecision(std::numeric_limits<double>::max_digits10);
	}
} fast; //cin,cout高速化のおまじない＋桁数指定

ll mll::MOD = (ll)(1e9 + 7);// 998244353ll;


ll LLpow(ll x, ll n) {
	ll ret = 1;
	while (n > 0) {
		if (n & 1) {
			ret *= x;
		}
		x *= x;
		n >>= 1;
	}
	return ret;
}

ll solve(vvll &block, ll y, ll x, ll K) {
	ll H = block.size();
	ll W = block[0].size();
	vvll B(H, vll(W));
	rep(i, H) rep(j, W) {
		B[i][j] = block[i][j];
	}
	ll ans = 0;
	ll times = 0;

	vector<vector<bool>> v(H, vector<bool>(W, false));
	v[y][x] = true;

	eprintf("\n<>--%lld, %lld--<>", y, x);

	while (true) {
		//eprintf("\n[%lld]\n", times-1);
		//rep(i, H) {
		//	rep(j, W) {
		//		eprintf("%lld ", B[i][j]);
		//	}
		//	eprintf("\n");
		//}

		//eprintf("vanish\n");
		//rep(i, H) {
		//	rep(j, W) {
		//		eprintf("%s ", v[i][j] ? "#" : ".");
		//	}
		//	eprintf("\n");
		//}

		//vanish->fall
		rep(i, W) {
			dep(j, H) {
				if (v[j][i]) {
					v[j][i] = false;
					bool fall = false;
					deps(k, j - 1, 0) {
						if (B[k][i] > 0 && v[k][i] == false) {
							fall = true;
							B[j][i] = B[k][i];
							v[k][i] = true;
							B[k][i] = 0;
							break;
						}
						else if (B[k][i] == 0) {
							B[j][i] = 0;
						}
					}
				}
			}
		}

		//eprintf("fallen\n");
		//rep(i, H) {
		//	rep(j, W) {
		//		eprintf("%lld ", B[i][j]);
		//	}
		//	eprintf("\n");
		//}

		//vanish
		ll vnum = 0;
		reps(j, 1, H - 1) {
			ll s = 0;
			ll e = -1;
			ll hold = 0;
			while (true) {
				e++;
				if (e >= W || B[j][e] != hold ) {
					//sからe-1までが同じ数字
					if (s < e && hold != 0) {
						if (e - s >= K) {
							//消える
							vnum += (e - s) * hold;
							reps(i, s, e - 1) {
								v[j][i] = true;
							}
						}
					}

					if (e >= W) {
						break;
					}
					else {
						hold = B[j][e];
						s = e;
					}
				}
			}
		}
		ans += vnum * LLpow(2, times);
		times++;

		if (vnum == 0) {
			break;
		}
	}
	
	eprintf("\nScore:%lld\n", ans);

	return ans;
}

int main() {
	ll H;
	cin >> H;
	ll W;
	cin >> W;
	ll K;
	cin >> K;
	vvll block(H, vll(W));
	rep(i, H){
		string S;
		cin >> S;
		rep(j, W) {
			block[i][j] = S[j] - '0';
		}
	}

	ll result = 0;

	reps(i, 1, H - 1) rep(j, W) {
		chmax(result, solve(block, i, j, K));
	}

	cout << result << endl;

	return 0;
}

Measured memory_bytes: 256