include<bits/stdc++.h>

include

include

include

using namespace std;
#define MAXSIZE 500
int main()
{
int n,i,sum,an,x;
while(cin>>n)
{
sum=0;
for(i=1 ; i<=n ; i++)
{
x=i;
while(x)
{
an=x%10;
if(an==1)
sum++;
x/=10;
}
}
cout<<sum<<endl;
}
return 0;
}