51Nod——N1284 2 3 5 7的倍数

 1 #include <cstdio>
 2 
 3 #define LL long long
 4 
 5 using namespace std;
 6 
 7 LL n,tot;
 8 
 9 int main()
10 {
11     scanf("%lld",&n);
12     tot=(LL)n/2+n/3+n/5+n/7;
13     tot-=(LL)(n/6+n/10+n/14+n/15+n/21+n/35);
14     tot+=(LL)n/30+n/42+n/70+n/105;
15     tot-=(LL)(n/210);
16     printf("%lld",n-tot);
17     return 0;
18 }