#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <iomanip>
using namespace std;
template<class T> inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; }
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class T> inline void POSS(T condition){ if(condition) cout << "POSSIBLE" << endl; else cout << "IMPOSSIBLE" << endl; }
template<class T> inline void Poss(T condition){ if(condition) cout << "Possible" << endl; else cout << "Impossible" << endl; }
template<class T> inline void First(T condition){ if(condition) cout << "First" << endl; else cout << "Second" << endl; }
template<class T = string, class U = char>int character_count(T text, U character){ int ans = 0; for(U i: text){ ans += (i == character); } return ans; }
long power(long base, long exponent, long module){ if(exponent % 2){ return power(base, exponent - 1, module) * base % module; }else if(exponent){ long root_ans = power(base, exponent / 2, module); return root_ans * root_ans % module; }else{ return 1; }}
struct position{ int y, x; }; position move_pattern[4] = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}}; // double euclidean(position first, position second){ return sqrt((second.x - first.x) * (second.x - first.x) + (second.y - first.y) * (second.y - first.y)); }
template<class T, class U> string to_string(pair<T, U> x){ return to_string(x.first) + "," + to_string(x.second); }
template<class itr> void array_output(itr start, itr goal){ string ans; for(auto i = start; i != goal; i++){ ans += to_string(*i) + " "; } ans.pop_back(); cout << ans << endl; }
template<class itr> void cins(itr start, itr goal){ for(auto i = start; i != goal; i++){ cin >> (*i); } }
template<class T> T gcd(T a, T b){ if(a && b){ return gcd(min(a, b), max(a, b) % min(a, b)); }else{ return a; }} template<class T> T lcm(T a, T b){ return a / gcd(a, b) * b; }
#define mod long(1e9 + 7)
#define all(x) (x).begin(), (x).end()
#define bitcount(n) __builtin_popcountl(long(n))
#define fcout cout << fixed << setprecision(20)
#define highest(x) (63 - __builtin_clzl(x))

int main(){
    int H, W, K;
    cin >> H >> W >> K;
    string space[H];
    for(int i = 0; i < H; i++){
        cin >> space[i];
    }
    int ans = 0;
    for(int i = 0; i < H; i++){
        for(int j = 0; j < W; j++){
            if(i != 3 || j != 2){
                ;
            }
            int this_ans = 0;
            string this_space[H];
            for(int k = 0; k < H; k++){
                this_space[k] = space[k];
            }
            this_space[i][j] = '0';
            for(int c = 0; true; c++){
                for(int k = 0; k < W; k++){
                    int not_0_count = 0;
                    for(int l = H - 1; l >= 0; l--){
                        if(this_space[l][k] != '0'){
                            char tmp = this_space[l][k];
                            this_space[l][k] = '0';
                            this_space[H - not_0_count - 1][k] = tmp;
                            not_0_count++;
                        }
                    }
                }
                int broke = 0;
                for(int k = 0; k < H; k++){
                    for(int l = 0; l < W; l++){
                        int serial = 1;
                        for(; l + serial < W; serial++){
                            if(this_space[k][l] != this_space[k][l + serial]){
                                break;
                            }
                        }
                        if(serial >= K && this_space[k][l] != '0'){
                            broke += (this_space[k][l] - '0') * serial;
                            for(int m = 0; m < serial; m++){
                                this_space[k][l + m] = '0';
                            }
                        }
                    }
                }
                if(!broke){
                    break;
                }else{
                    this_ans += int(power(2, c, 1e18)) * broke;
                }
            }
            ans = max(ans, this_ans);
        }
    }
    cout << ans << endl;
}


Measured memory_bytes: 256