#include<bits/stdc++.h>
using namespace std;
const int N = 3e6+20, M = 1e6+10, mod = 1e9+7,inf = 1e9+1;

typedef long long ll;

ll ans;
int x,a[N],n,m;
ll gcd(ll a,ll b) {return b==0?a:gcd(b,a%b);}
void dfs(int i,int num,ll tmp) {
     if(i>=m) {
        if(num==0) ans=0;
        else {
            if(num&1) ans = (ans+n/tmp);
            else ans = ans - n/tmp;
        }
        return ;
     }
     dfs(i+1,num,tmp);
     dfs(i+1,num+1,tmp*a[i]/gcd(tmp,a[i]));
}
int main() {
    while(scanf("%d%d",&n,&m)!=EOF) {
        int k = 0;
        n--;
        for(int i=1;i<=m;i++) {
            scanf("%d",&x);
            if(x) a[k++] = x;
        }
        m = k;
        ans = 0;
        dfs(0,0,1);
        printf("%I64d\n",ans);
    }
    return 0;
}