1284 2 3 5 7的倍数

 1 #include <bits/stdc++.h>
 2 #define ll long long int
 3 using namespace std;
 4 int main(){
 5   ll n;
 6   scanf("%lld",&n);
 7   ll a=n/2,b=n/3,c=n/5,d=n/7; //满足一个条件
 8   ll ab=n/6,ac=n/10,ad=n/14,bc=n/15,bd=n/21,cd=n/35; //满足两个条件
 9   ll abc=n/30,abd=n/42,acd=n/70,bcd=n/105; //满足三个条件
10   ll abcd=n/210; //满足四个条件
11   ll ans=(a+b+c+d)-(ab+ac+ad+bc+bd+cd)+(abc+abd+acd+bcd)-(abcd);
12   printf("%lld\n",n-ans);
13   return 0;
14 }