/* -*- coding: utf-8 -*-
 *
 * 3711.cc:  No.3711 Udon, Tempura - yukicoder
 */

#include<cstdio>
#include<bitset>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 100;
const int MAX_M = 100;
const int MAX_U = 100000;
const int MAX_T = 1000;
const int MAX_S = MAX_U + MAX_M * MAX_T;

/* typedef */

using btst = bitset<MAX_S + 1>;

/* global variables */

int us[MAX_N], ts[MAX_M];

/* subroutines */

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%d", us + i);
  for (int i = 0; i < m; i++) scanf("%d", ts + i);

  btst dp;
  dp[0] = 1;
  for (int i = 0; i < m; i++) dp |= (dp << ts[i]);

  btst b;
  for (int i = 0; i < n; i++) b |= (dp << us[i]);

  printf("%d\n", (int)b.count());
  
  return 0;
}