One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.
#include <bits/stdc++.h>
using namespace std;
int ok(int n) {
  int valid = 1;
  while (n != 0) {
    if (n % 10 != 0 && n % 10 != 1) valid = 0;
    n = n / 10;
  }
  return valid;
}
int a[] = {1,         10,         11,        100,       101,       110,
           111,       1000,       1001,      1010,      1011,      1100,
           1101,      1110,       1111,      10000,     10001,     10010,
           10011,     10100,      10101,     10110,     10111,     11000,
           11001,     11010,      11011,     11100,     11101,     11110,
           11111,     100000,     100001,    100010,    100011,    100100,
           100101,    100110,     100111,    101000,    101001,    101010,
           101011,    101100,     101101,    101110,    101111,    110000,
           110001,    110010,     110011,    110100,    110101,    110110,
           110111,    111000,     111001,    111010,    111011,    111100,
           111101,    111110,     111111,    1000000,   1000001,   1000010,
           1000011,   1000100,    1000101,   1000110,   1000111,   1001000,
           1001001,   1001010,    1001011,   1001100,   1001101,   1001110,
           1001111,   1010000,    1010001,   1010010,   1010011,   1010100,
           1010101,   1010110,    1010111,   1011000,   1011001,   1011010,
           1011011,   1011100,    1011101,   1011110,   1011111,   1100000,
           1100001,   1100010,    1100011,   1100100,   1100101,   1100110,
           1100111,   1101000,    1101001,   1101010,   1101011,   1101100,
           1101101,   1101110,    1101111,   1110000,   1110001,   1110010,
           1110011,   1110100,    1110101,   1110110,   1110111,   1111000,
           1111001,   1111010,    1111011,   1111100,   1111101,   1111110,
           1111111,   10000000,   10000001,  10000010,  10000011,  10000100,
           10000101,  10000110,   10000111,  10001000,  10001001,  10001010,
           10001011,  10001100,   10001101,  10001110,  10001111,  10010000,
           10010001,  10010010,   10010011,  10010100,  10010101,  10010110,
           10010111,  10011000,   10011001,  10011010,  10011011,  10011100,
           10011101,  10011110,   10011111,  10100000,  10100001,  10100010,
           10100011,  10100100,   10100101,  10100110,  10100111,  10101000,
           10101001,  10101010,   10101011,  10101100,  10101101,  10101110,
           10101111,  10110000,   10110001,  10110010,  10110011,  10110100,
           10110101,  10110110,   10110111,  10111000,  10111001,  10111010,
           10111011,  10111100,   10111101,  10111110,  10111111,  11000000,
           11000001,  11000010,   11000011,  11000100,  11000101,  11000110,
           11000111,  11001000,   11001001,  11001010,  11001011,  11001100,
           11001101,  11001110,   11001111,  11010000,  11010001,  11010010,
           11010011,  11010100,   11010101,  11010110,  11010111,  11011000,
           11011001,  11011010,   11011011,  11011100,  11011101,  11011110,
           11011111,  11100000,   11100001,  11100010,  11100011,  11100100,
           11100101,  11100110,   11100111,  11101000,  11101001,  11101010,
           11101011,  11101100,   11101101,  11101110,  11101111,  11110000,
           11110001,  11110010,   11110011,  11110100,  11110101,  11110110,
           11110111,  11111000,   11111001,  11111010,  11111011,  11111100,
           11111101,  11111110,   11111111,  100000000, 100000001, 100000010,
           100000011, 100000100,  100000101, 100000110, 100000111, 100001000,
           100001001, 100001010,  100001011, 100001100, 100001101, 100001110,
           100001111, 100010000,  100010001, 100010010, 100010011, 100010100,
           100010101, 100010110,  100010111, 100011000, 100011001, 100011010,
           100011011, 100011100,  100011101, 100011110, 100011111, 100100000,
           100100001, 100100010,  100100011, 100100100, 100100101, 100100110,
           100100111, 100101000,  100101001, 100101010, 100101011, 100101100,
           100101101, 100101110,  100101111, 100110000, 100110001, 100110010,
           100110011, 100110100,  100110101, 100110110, 100110111, 100111000,
           100111001, 100111010,  100111011, 100111100, 100111101, 100111110,
           100111111, 101000000,  101000001, 101000010, 101000011, 101000100,
           101000101, 101000110,  101000111, 101001000, 101001001, 101001010,
           101001011, 101001100,  101001101, 101001110, 101001111, 101010000,
           101010001, 101010010,  101010011, 101010100, 101010101, 101010110,
           101010111, 101011000,  101011001, 101011010, 101011011, 101011100,
           101011101, 101011110,  101011111, 101100000, 101100001, 101100010,
           101100011, 101100100,  101100101, 101100110, 101100111, 101101000,
           101101001, 101101010,  101101011, 101101100, 101101101, 101101110,
           101101111, 101110000,  101110001, 101110010, 101110011, 101110100,
           101110101, 101110110,  101110111, 101111000, 101111001, 101111010,
           101111011, 101111100,  101111101, 101111110, 101111111, 110000000,
           110000001, 110000010,  110000011, 110000100, 110000101, 110000110,
           110000111, 110001000,  110001001, 110001010, 110001011, 110001100,
           110001101, 110001110,  110001111, 110010000, 110010001, 110010010,
           110010011, 110010100,  110010101, 110010110, 110010111, 110011000,
           110011001, 110011010,  110011011, 110011100, 110011101, 110011110,
           110011111, 110100000,  110100001, 110100010, 110100011, 110100100,
           110100101, 110100110,  110100111, 110101000, 110101001, 110101010,
           110101011, 110101100,  110101101, 110101110, 110101111, 110110000,
           110110001, 110110010,  110110011, 110110100, 110110101, 110110110,
           110110111, 110111000,  110111001, 110111010, 110111011, 110111100,
           110111101, 110111110,  110111111, 111000000, 111000001, 111000010,
           111000011, 111000100,  111000101, 111000110, 111000111, 111001000,
           111001001, 111001010,  111001011, 111001100, 111001101, 111001110,
           111001111, 111010000,  111010001, 111010010, 111010011, 111010100,
           111010101, 111010110,  111010111, 111011000, 111011001, 111011010,
           111011011, 111011100,  111011101, 111011110, 111011111, 111100000,
           111100001, 111100010,  111100011, 111100100, 111100101, 111100110,
           111100111, 111101000,  111101001, 111101010, 111101011, 111101100,
           111101101, 111101110,  111101111, 111110000, 111110001, 111110010,
           111110011, 111110100,  111110101, 111110110, 111110111, 111111000,
           111111001, 111111010,  111111011, 111111100, 111111101, 111111110,
           111111111, 1000000000, 1000000001};
int main() {
  int n;
  cin >> n;
  int i = 0;
  while (n >= a[i]) {
    i++;
  }
  cout << i << endl;
  return 0;
}
