#include <iostream>
#include <math.h>

using namespace std;

int main(int argc, char** argv) {
    int n,m,k;
    scanf("%d %d %d",&n,&m,&k);
    int ret = 0;
    for(int i = 0; i < n; i++) {
        int addition = 0;
        for(int j = 0; j < m; j++) {
            int cost;
            scanf("%d",&cost);
            int additionn = cost-k*(j+1);
            if(additionn > addition)
            {
                addition = additionn;
            }
        }
        ret += addition;
    }
    cout << ret << endl;
    return 0;
}