// 动态规划
#include <bits/stdc++.h>
using namespace std;

const int N = 210;
int n, m, k;
string g[N];
int w[N][N];
int f[N][N];

const int MIN_INT =  -0x3f3f3f3f;

int main(){

    cin >> n >> m >> k;

    // 输入
    for(int i=1;i<=n;i++){
        cin >> g[i];
        g[i] = " "+g[i];
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++)
            cin >> w[i][j];
    }

    // 递归
    int res = -1;

    // 初始化
    // f[1][1] = 0;
    // f[0][j] 不可能
    // f[i][0] 不可能

    f[1][1] = 0;
    for(int i=1;i<=n;i++) f[i][0] = MIN_INT;
    for(int j=1;j<=m;j++) f[0][j] = MIN_INT;


    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){

            char x = g[i][j];
                        // if(i == 1 && j == 2) cout<<x<<endl;
            int u = w[i][j];

            char a = g[i][j-1]; // 相等
                        // if(i == 1 && j == 2) cout<<a<<endl;

            char b = g[i-1][j];

            if(x == a) f[i][j] = max(f[i][j-1]+u, f[i][j]);
            else f[i][j] = max(f[i][j], f[i][j-1]+u-k);

            // if(i == 1 && j == 2) cout<<f[i][j]<<endl;

            if(x == b) f[i][j] = max(f[i-1][j]+u, f[i][j]);
            else f[i][j] = max(f[i][j], f[i-1][j]+u-k);

            // if(i == 1 && j == 2) cout<<f[i][j]<<endl;

            // cout<<f[i][j]<<" ";

            res = max(res, f[i][j]);
        }
        // cout<<endl;
    }

    cout<<res<<endl;
    // cout<<f[1][1]<<endl;

    return 0;
}