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>
const int ans[] = {
    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};
int main(void) {
  int n;
  scanf("%d", &n);
  if (n == 1000000000) return printf("512"), 0;
  for (int i = 0; i < 512; i++)
    if (ans[i] > n) {
      printf("%d", i);
      break;
    }
  return 0;
}
