import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.BufferedWriter;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        C755 solver = new C755();
        solver.solve(1, in, out);
        out.close();
    }

    static class C755 {
        public void solve(int testNumber, InputReader in, OutputWriter out) {
            String s = in.nextString();
            int n = Integer.valueOf(s);
            int[] res = new int[1];
            dfs("", n, s.length(), res);
            out.println(res[0]);
        }

        private void dfs(String s, int n, int length, int[] res) {
            if (s.length() > length) return;

            if (s.length() > 0 && pass(s) && Integer.valueOf(s) <= n) {
                res[0]++;
            }


            dfs(s + 3, n, length, res);
            dfs(s + 5, n, length, res);
            dfs(s + 7, n, length, res);
        }

        private boolean pass(String num) {
            boolean found3 = false;
            boolean found5 = false;
            boolean found7 = false;
            for (int i = 0; i < num.length(); i++) {
                if (num.charAt(i) == '3') found3 = true;
                else if (num.charAt(i) == '5') found5 = true;
                else if (num.charAt(i) == '7') found7 = true;
                else return false;
            }

            return found3 && found5 && found7;
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public String nextString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                if (Character.isValidCodePoint(c)) {
                    res.appendCodePoint(c);
                }
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void close() {
            writer.close();
        }

        public void println(int i) {
            writer.println(i);
        }

    }
}



Measured memory_bytes: 35088