
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        }
    } main {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (sc.hasNextInt()) {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        } sc.hasNextInt() sc.hasNextInt sc {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        } char[] s = sc.next().toCharArray(); s sc.next().toCharArray() sc.next().toCharArray sc.next() sc.next sc int ans = 0; ans 0 for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            } char c s {
                if ( c == '1' ) {
                    ans++;
                }
            } {
                if ( c == '1' ) {
                    ans++;
                }
            } if ( c == '1' ) {
                    ans++;
                } c == '1' c '1' {
                    ans++;
                } ans++ ans System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        }
    }
} Main

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            char[] s = sc.next().toCharArray();
            int ans = 0;
            for (char c : s) {
                if ( c == '1' ) {
                    ans++;
                }
            }
            System.out.println(ans);
        }
    }
}
