Information
- ID
- 6767
- Time
- 1000ms
- Memory
- 256MiB
- Difficulty
- 7
- Tags
- # Submissions
- 348
- Accepted
- 82
- Uploaded By
#include<iostream>
using namespace std;
int Judge(int n){
/*if(n==1){
return 0;
}
else*/
//省去无效计算
for(int i=2;i*i<=n;i++){
if(n%i==0){
return 0;
}
}
return 1;
}
int main(){
int n,sum=0;
cin>>n;
for(int i=2;i<=n;i++){
sum+=Judge(i);
}
cout<<sum;
return 0;
}
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