import java.io.IOException;
import java.io.InputStream;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NoSuchElementException;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Scanner;
import java.util.Set;

public class Main {

	static Scanner sc = new Scanner(System.in);

	static class FastScanner {
		private final InputStream in;
		private final byte[] buffer = new byte[1024];
		private int ptr = 0;
		private int buflen = 0;

		public FastScanner(InputStream source) {
			in = source;
		}

		private boolean hasNextByte() {
			if (ptr < buflen) {
				return true;
			} else {
				ptr = 0;
				try {
					buflen = in.read(buffer);
				} catch (IOException e) {
					e.printStackTrace();
				}
				if (buflen <= 0) {
					return false;
				}
			}
			return true;
		}

		private int readByte() {
			if (hasNextByte()) return buffer[ptr++];
			else return -1;
		}

		private static boolean isPrintableChar(int c) {
			return 33 <= c && c <= 126;
		}

		public boolean hasNext() {
			while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
			return hasNextByte();
		}

		public String next() {
			if (!hasNext()) throw new NoSuchElementException();
			StringBuilder sb = new StringBuilder();
			int b = readByte();
			while (isPrintableChar(b)) {
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		public long nextLong() {
			if (!hasNext()) throw new NoSuchElementException();
			long n = 0;
			boolean minus = false;
			int b = readByte();
			if (b == '-') {
				minus = true;
				b = readByte();
			}
			if (b < '0' || '9' < b) {
				throw new NumberFormatException();
			}
			while (true) {
				if ('0' <= b && b <= '9') {
					n *= 10;
					n += b - '0';
				} else if (b == -1 || !isPrintableChar(b)) {
					return minus ? -n : n;
				} else {
					throw new NumberFormatException();
				}
				b = readByte();
			}
		}

		public int nextInt() {
			long nl = nextLong();
			if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
				throw new NumberFormatException();
			return (int) nl;
		}

		public double nextDouble() {
			return Double.parseDouble(next());
		}
	}

	public static void main(String[] args){

		solve_abc166_c();
	}
  
  	public static void solve_abc166_c(){

		FastScanner sc = new FastScanner(System.in);
		
		
		int n = sc.nextInt();
		int m = sc.nextInt();
		int q = sc.nextInt();
		
		int[] ai = new int[q];
		int[] bi = new int[q];
		int[] ci = new int[q];
		int[] di = new int[q];
		
		for(int i=0;i<q;i++){
			ai[i] = sc.nextInt();
			bi[i] = sc.nextInt();
			ci[i] = sc.nextInt();
			di[i] = sc.nextInt();
		}
		
		int[] tmp = new int[n];
		
		List<int[]> a = new ArrayList<int[]>();
		
		solve_abc166_c_permutation(n, m, 0, 1, tmp, a);
		long ans = 0;
		
		for(int[] x: a){
			
			//for(int i=0;i<x.length;i++) System.out.print(x[i] +" ");
			
			
			long tmpans = 0;
			
			for(int i=0;i<q;i++){
				if((x[bi[i]-1]-x[ai[i]-1]) == ci[i]) tmpans += (long)di[i];
			}
			
			if(tmpans > ans){
				ans = tmpans;
			}
		}
		
		System.out.println(ans);
	}
	
	public static void solve_abc166_c_permutation(int n,  int m, int idxs, int valprv, int[] ans, List<int[]> ansList){
		
		if(n == 0){
			ansList.add(ans.clone());
			return;
		}
		
		for(int i=valprv;i<=m;i++){
			ans[idxs] = i;
			solve_abc166_c_permutation(n-1,  m, idxs+1, i, ans, ansList);
		}
	}
}

Measured memory_bytes: 34264