630K - Indivisibility - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;
typedef long long l1;
#define ios ios::sync_with_stdio(false);cin.tie(0);
#define rep(i, a, n) for(int (i) = (int)a; (i) < (int)(n); ++(i))
#define REP(i, a, n) for(int (i) = (int)a; (i) <= (int)(n); ++(i))
const l1 MOD = 1e9 + 7;
template <typename T>
void print(vector<T>v)
{
    for(auto it: v)cout<<it<<" ";
    cout<<"\n";
}
l1 n;
int main()
{
    ios
    int test = 1;
    //cin >> test;
    while(test--)
    {
        //l1 n;
        cin >> n;
        vector<l1>v = {2,3,5,7};
        l1 ans = n;
        rep(a, 0, 4)ans-= n/v[a];
        rep(a, 0, 4)
        {
            rep(b, a+1, 4)ans+= n/(v[a]*v[b]);
        }
        rep(a, 0, 4)
        {
            rep(b, a+1, 4)
            {
                rep(c, b+1, 4)ans-= n/(v[a]*v[b]*v[c]);
            }
        }
        ans+= n/(v[0]*v[1]*v[2]*v[3]);
        cout<<ans;
    }
}