12 2
2 3

7

#include <cstdio>
#include <cstring>
#include <algorithm>
#define ll long long
using namespace std;
int a[25], b[25];
ll ans;
int n, m, cnt;

ll gcd(ll a, ll b)
{
    return b ? gcd(b, a % b) : a;  
}

ll lcm(int a, int b)
{
    return (ll) a * b / gcd(a, b);
}

void DFS(int idx, ll cur, int sgin)
{
    for(int i = idx; i < cnt; i++)
    {
        ll tmp = lcm(cur, (ll)b[i]);
        ans += (ll) sgin * (n / tmp);
        DFS(i + 1, tmp, -sgin);
    }
}

int main()
{
    while(scanf("%d %d", &n, &m) != EOF)
    {
        n --;
        cnt = 0;
        bool flag = false;
        for(int i = 0; i < m; i++)
        {
            scanf("%d", &a[i]);
            if(a[i] != 0)
                b[cnt ++] = a[i];
            if(a[i] == 1)
                flag = true;
        }
        if(flag)
        {
            printf("%d\n", n);
            continue;
        }
        sort(b, b + cnt);
        ans = 0;
        DFS(0, 1, 1);
        printf("%I64d\n", ans);
    }
}