#include<iostream>

using namespace std;
int N,ans;

void dfs(long long x, bool flag3, bool flag5, bool flag7)
{if(x > N){return ;}
 if(flag3 && flag5 && flag7){ans++;}
 
 dfs(10*x + 3, true, flag5,flag7);
 dfs(10*x + 5, flag3, true, flag7);
 dfs(10*x + 7, flag3, flag5, true);
}

int main()
{cin >> N; 
 ans = 0;
 dfs(0,0,0,0);
 cout << ans << endl;
 return 0;
}
