#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
   ll dp[20] = {};//10^iで命題を満たす数
   dp[1] = 3;
   ll num = 10;
   rep(i,2,20){
       dp[i] = dp[i-1] * 9 + 9 + (num - 1);
       num *= 10;
   }
   int N;
   cin >> N;
   cout << dp[N] << endl;
}