#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iterator>
#include <bitset>
#include <unordered_set>
#include <unordered_map>
#include <fstream>
#include <iomanip>
#include <cassert>
//#include <utility>
//#include <memory>
//#include <functional>
//#include <deque>
//#include <cctype>
//#include <ctime>
//#include <numeric>
//#include <list>
//#include <iomanip>

//#if __cplusplus >= 201103L
//#include <array>
//#include <tuple>
//#include <initializer_list>
//#include <forward_list>
//
//#define cauto const auto&
//#else

//#endif

using namespace std;


typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vint;
typedef vector<vector<int> > vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long> > vvll, vvLL;

#define VV(T) vector<vector< T > >

template <class T>
void initvv(vector<vector<T> > &v, int a, int b, const T &t = T()){
    v.assign(a, vector<T>(b, t));
}

template <class F, class T>
void convert(const F &f, T &t){
    stringstream ss;
    ss << f;
    ss >> t;
}

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define reep(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) reep((i),0,(n))
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(),(v).rend()
#define DEBUG
#ifdef DEBUG
#define dump(x)  cout << #x << " = " << (x) << endl;
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
#else
#define dump(x) 
#define debug(x) 
#endif

#define MOD 1000000007LL
#define EPS 1e-8
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define maxs(x,y) x=max(x,y)
#define mins(x,y) x=min(x,y)

void mainmain(){
	int H, W, K;
	cin>>H>>W>>K;
	vvint vv;
	initvv(vv,H,W);
	rep(i,H) rep(j,W){
		char t;
		cin>>t;
		vv[i][j] = t - '0';
	}
	int ans = 0;
	rep(_i,H){
		rep(_j,W){
			vvint ww = vv;
			ww[_i][_j] = 0;
			bool update = true;
			int cnt = 1;
			int tmp = 0;
			// cout << "i j "<< _i << " "<<_j<<endl;
			while(update){
				update = false;
				int sum = 0;
				rep(j,W){
					for(int i=H-1;i>=0;i--){
						int p = i;
						while(ww[p][j] && p+1 < H && ww[p+1][j] == 0){
							ww[p+1][j] = ww[p][j];
							ww[p][j] = 0;
							p++;
						}
					}
				}
				// rep(i,H){
				// 	rep(j,W){
				// 		cout<<" "<<ww[i][j];
				// 	}cout<<endl;
				// }cout<<endl;
				rep(i,H){
					rep(j,W){
						if(j+K-1>=W) break;
						if(!ww[i][j]) continue;
						bool ok = true;
						reep(k,j+1,j+K){
							if(ww[i][j] != ww[i][k]) ok=false;
						}
						if(ok){
							update = true;
							int t = ww[i][j];
							while(j < W && t == ww[i][j]){
								sum += ww[i][j];
								ww[i][j] = 0;
								j++;
							}
							j--;
						}
					}
				}
				tmp += cnt * sum;
				cnt <<= 1;
			}
			maxs(ans, tmp);
		}
	}
	cout << ans << endl;
}


signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout<<fixed<<setprecision(20);
    mainmain();
}

Measured memory_bytes: 256