容斥原理

#include<cstdio>
#include<cstring>
#include<iostream>
#define INF 99999999
#define ll __int64
using namespace std;
ll slove(ll n)
{
ll osum1,osum2,osum3,osum4;
osum1 = n/2;
osum2 = n/3;
osum3 = n/5;
osum4 = n/7;
ll ans = osum1+osum2+osum3+osum4;
ans = ans - n/(2*3) - n/(2*7) - n/(2*5) - n/(3*5) - n/(3*7) - n/(5*7);
ans = ans + n/(2*3*5) + n/(2*3*7) + n/(3*5*7) + n/(2*5*7);
ans = ans - n/(2*3*5*7);
return ans;
}
int main()
{
ll n;
while(~scanf("%I64d",&n)){
cout<<n - slove(n)<<endl;
}
}