复制不了你就受着呗

#include <bits/stdc++.h>
using namespace std;
int sum=0,b;
int main(){
int n;
cin>>n;
for(int i=1;i<=n;i++){
b=i;
while(b!=0){
if(b%10==1) sum+=1;
b/=10;
}
}
cout<<sum;

return 0;

}