题解 | #挑7#

#include <algorithm>

using namespace std;

bool judge(int x){
    if(x%7==0) return true;
    while(x!=0){
        if(x%10==7) return true;
        x/=10;
    }
    return false;
    
}


int main() {
    int N;
    while(cin>>N){
        bool relation = false;
        int cnt=0;
        
       for(int i = 1;i<=N;i++)
       {
           relation = judge(i);
           if(relation) cnt++;
           
           
       }
        cout<<cnt<<endl;
    }
}