#include <iostream>
#include <cstring>
#include <stdio.h>
#include <cstdlib>

int main() {
    int n = 0; char* toint; int d_counter[10];
scanf("%i",&n);
for(int i = 1;i <= n;i++)
{
   itoa(i, toint, 10);
   for(int i2 = 0;i2 <= 10;i2++)
   {
      for (int i3 = 0;i3 < strlen(toint);i3++)
{
      if (toint[i3] == i2)
      if (d_counter[i2]+1==2)
{
n++;
goto end;
}
   }
}
end:
}
printf("%i", n);
    return 0;
}