#include <iostream>
#include <vector>

int main()
{
    int l, c;
    std::cin >> l >> c;
    std::vector<int> eat(c);
    for(int i = 0; i != c; ++i)
        std::cin >> eat[i];

    int cl = 0;
    for(int i = 1; i <= l; ++i)
    {
        bool e = false;
        for(auto& v: eat){
            if(!(i % v)){
                e = true;
                break;
            }
        }
        if(!e)
            ++cl;
    }
    std::cout << cl << std::endl;
}