#include using namespace std; #define fs first #define sc second #define pb push_back #define mp make_pair #define eb emplace_back #define ALL(A) A.begin(),A.end() #define RALL(A) A.rbegin(),A.rend() typedef long long LL; typedef pair P; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } template T gcd(T a,T b){return b?gcd(b,a%b):a;} const LL mod=1000000007; const LL LINF=1LL<<62; const int INF=1<<30; int dx[]={1,0,-1,0,-1,1,1,-1}; int dy[]={0,1,0,-1,-1,-1,1,1}; LL ans; LL n; set st; void dfs(LL k, LL p){ if(n < k || p > n * 10) return ; if(100 <= k && k % 3 == 0){ st.insert(k); } dfs(k + 0 * p, p * 10); dfs(k + 3 * p, p * 10); dfs(k + 6 * p, p * 10); dfs(k + 9 * p, p * 10); } int main(){ cin >> n; if(n < 100){ for (int i = 12; i <= n; i+=3) { if(((i % 10) + (i / 10))%3 == 0) ans++; } } else{ for (int i = 12; i < 100; i+=3) { if(((i % 10) + (i / 10))%3 == 0) ans++; } dfs(0, 1); ans += st.size(); } cout << ans << endl; return 0; }