#include <inttypes.h>
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
    intmax_t N, M, Q, a[50], b[50], c[50], d[50];
    intmax_t A[10];
    intmax_t ans = 0;

    scanf("%jd%jd%jd", &N, &M, &Q);
    for (size_t i = 0; i < Q; i++) {
        scanf("%jd%jd%jd%jd", &a[i], &b[i], &c[i], &d[i]);
    }

    for (A[0] = 0; A[0] <= M; A[0]++) {
        for (A[1] = A[0]; A[1] <= M; A[1]++) {
            for (A[2] = A[1]; A[2] <= M; A[2]++) {
                for (A[3] = A[2]; A[3] <= M; A[3]++) {
                    for (A[4] = A[3]; A[4] <= M; A[4]++) {
                        for (A[5] = A[4]; A[5] <= M; A[5]++) {
                            for (A[6] = A[5]; A[6] <= M; A[6]++) {
                                for (A[7] = A[6]; A[7] <= M; A[7]++) {
                                    for (A[8] = A[7]; A[8] <= M; A[8]++) {
                                        for (A[9] = A[8]; A[9] <= M; A[9]++) {
                                            intmax_t tmp = 0;
                                            for (size_t i = 0; i < Q; i++) {
                                                if (A[b[i] - 1] - A[a[i] - 1] == c[i]) {
                                                    tmp += d[i];
                                                }
                                            }
                                            if (tmp > ans)
                                                ans = tmp;
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }

    printf("%jd\n", ans);

    return 0;
}
