1017F - The Neutral Zone - CodeForces Solution

#include<bits/stdc++.h>
using u=uint32_t;u n,a,b,c,d,e,i,j,f;std::bitset<int(1e8)>z;
u g(u x){u m=a*x*x*x+b*x*x+c*x+d;for(u f=n;f;f/=x)e+=f/x*m;}
main(){std::cin>>n>>a>>b>>c>>d;;g(2),g(3);for(i=5,j=2;i<=n;i+=j,j=6-j){if(!z[i/3]){g(i);if(i<=n/i)for(u k=i*i,l=j;k<=n;k+=i*l,l=6-l)z[k/3]=1;}}std::cout<<e;}