#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
typedef long long ll;
ll Num[30];
ll gcd(ll a,ll b)
{
    return b == 0 ? a : gcd(b,a%b);
}
int main()
{
    ll N, M;
    while(scanf("%lld%lld",&N,&M)!=EOF)
    {
        N--;
        ll num = 0;
        ll tmp,Cnt 
 
= 0;
        for(int i = 0; i < M; ++i)
        {
            scanf("%lld",&tmp);
            if(tmp == 0) continue;
            else {
                Num[Cnt++] = tmp;
            }
        }
        for(int i = 1; i < (1 << Cnt) ; ++i)
        {
            ll cnt = 0, tmp = 1;
            
 
for(int j = 0; j < Cnt; ++j)
            {
                if(i & (1 << j))
                {
                    cnt++;
                    tmp =tmp /gcd(tmp,Num[j]) * Num[j];
                }
                //printf("%lld\n",tmp);
            }
            if(cnt & 1) num += (N/tmp);
            
 
else num -= (N/tmp);
        }
        printf("%lld\n",num);
    }
    return 0;
}