20分

#include<set>
#include<map>
#include<list>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<ctime>
#include<cfloat>
#include<cctype>
#include<cstdio>
#include<cwchar>
#include<vector>
#include<bitset>
#include<string>
#include<memory>
#include<cstring>
#include<cassert>
#include<csignal>
#include<cstdlib>
#include<cwctype>
#include<cstddef>
#include<utility>
#include<numeric>
#include<iomanip>
#include<iterator>
#include<iostream>
#include<algorithm>
#include<functional>
#define N 10000010
using namespace std;
bool v[N];
int p[N];
int pd(int n){
    int cnt=0;
    memset(v,0,sizeof(v));
    memset(p,0,sizeof(p));
    for(int i=2;i<=n;i++){
    	if(!v[i]){
    		p[cnt++]=i;
		}
		for(int j=0;j<cnt;j++){
			if(i*p[j]>n){
				break;
			}
			v[i*p[j]]=1;
			if(i%p[j]==0){
				break;
			}
		}
	}
	return cnt;
}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	int w=pd(200);
	int n,s=0,c=0;
	cin>>n;
	for(int i=0;i<w;i++){
		if(s+p[i]<=n){
			s+=p[i];
			c++;
		}else{
			break;
		}
	}
	cout<<c;
	return 0;
}