#include <iostream> #include <cstdio> #include <iomanip> using namespace std; int main(){ int n,i,ans=0,a,b,c,d,e; cin>>n; for(i=11;i<=n;i++){ a=i/10000; b=i/1000%10; c=i/100%10; d=i/10%10; e=i%10; if (a<=b&&b<=c&&c<=d&&d<=e){ ans+=1; } } cout<<ans; return 0; }