#include <cstdio>

#define in "light2.in"
#define out "light2.out"
#define LL long long
#define BULB 30

using namespace std;
int v[BULB], v1[BULB], m;
LL v2[BULB], ans, n, tmp, nr = 1;

LL cmmmc(LL a,LL b)
{
    if(a==0) a=1;
    if(b==0) b=1;
    LL tmp1=a*b, tmp2=a%b;
    while(tmp2)
    {
        a=b;b=tmp2;
        tmp2=a%b;
    }
    return tmp1/b;
}
inline void init()
{
    tmp = m;
    ans = n/v[m];
    v1[m-1] = 1;
    v2[nr] = v[m-1];
}
inline void solve()
{
    while(tmp)
    {
        if(tmp == m)
        {
            //printf("%lld %d\n", v2[nr], nr);
            //printf("check1\n");
            if(nr&1) ans += (n/v2[nr]) * (1LL<<(nr-1)) - (n/cmmmc(v2[nr], v[tmp])) * (1LL<<nr);
            else ans -= (n/v2[nr]) * (1LL<<(nr-1)) - (n/cmmmc(v2[nr], v[tmp])) * (1LL<<nr);
            --tmp;
            continue;
        }
        if(!v1[tmp])
        {
            //printf("check2\n");
            v1[tmp] = 1;
            v2[++nr] = cmmmc(v2[nr-1], v[tmp]);
            //printf("%lld\n", cmmmc(v2[nr-1], v[tmp]));
            tmp = m;
            continue;
        }
        //printf("check3\n");
        v1[tmp] = 0;
        --nr;
        --tmp;
    }
}

int main()
{
    freopen(in, "r", stdin);
    freopen(out, "w", stdout);
    scanf("%lld%d", &n, &m);
    for(int i = 1; i<= m; ++i) scanf("%d", &v[i]);
    init();
    solve();
    printf("%lld\n", ans);
    return 0;
}