C :

#include <stdio.h>
#include <string.h>
#include <limits.h>

int main(){
	
	int m, n, i, j, k, maxIcomes, tmp, flag;
	int pay[128][128], incomes[128][128], maxIcomesEveryDayAndCity[2][128];
	
	while (1){
		
		scanf("%d%d", &n, &m);
		if (n==0 && m==0){
			break;
		}
		
		for (i = 1; i <= n; i++){
			for (j = 1; j <= n; j++){
				scanf("%d", &pay[i][j]);
			}
		}
		
		for (i = 1; i <= m; i++){
			for (j = 1; j <= n; j++){
				scanf("%d", &incomes[i][j]);
			}
		}
		
		memset(maxIcomesEveryDayAndCity, -128, sizeof(maxIcomesEveryDayAndCity));
		maxIcomesEveryDayAndCity[0][1] = 0;
		flag = 0;
		for (i = 1; i <= m; i++){
			flag = !flag;
			for (j = 1; j <= n; j++){
				for (k = 1; k <= n; k++){
					tmp = maxIcomesEveryDayAndCity[!flag][k] + incomes[i][j] - pay[k][j];
					if (tmp > maxIcomesEveryDayAndCity[flag][j]){
						maxIcomesEveryDayAndCity[flag][j] = tmp;
					}
				}
			}
		}
		
		maxIcomes = INT_MIN;
		for (i = 1; i <= n; i++){
			if (maxIcomesEveryDayAndCity[flag][i] > maxIcomes){
				maxIcomes = maxIcomesEveryDayAndCity[flag][i];
			}
		}
		
		printf("%d\n", maxIcomes);
	}
	
	return 0;
}

C++ :

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
using namespace std;
const int MAX = 100;
int cost[MAX+2][MAX+2];
int income[MAX+2][MAX+2];
int ans[MAX+2][MAX+2];
int main()
{
    int n, m;
    int temp;

    while (scanf("%d%d", &n, &m) && n && m)
    {
        memset(income, 0 ,sizeof(income));
        memset(cost, 0 ,sizeof(cost));
        memset(ans, 0, sizeof(ans));
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= n; j++) scanf("%d", &cost[i][j]);
        }
        for (int i = 1; i <= m; i++)
        {
            for (int j = 1; j <= n; j++) scanf("%d", &income[i][j]);
        }
        for (int i = 1; i <= n; i++) ans[1][i] = income[1][i] - cost[1][i];
        for (int i = 2; i <= m; i++)
            for (int j = 1; j <= n; j++)
                for (int k = 1; k <= n; k++)
                {
                    ans[i][j] = max(ans[i][j], ans[i-1][k] + income[i][j] - cost[k][j]);
                }

        int max_ans = 0;
        for (int i = 1; i <= n; i++) max_ans = max(max_ans, ans[m][i]);
        printf("%d\n", max_ans);
    }
    return 0; 
}