import java.util.*;
public class Main{
  public static void main(String[] args) {
    Scanner sc = new Scanner (System.in);
    String s = sc.next();
    char a[] = new char[3];
    int count = 0;
    for(int i=0 ; i<3 ; i++){
      a[i] = s.charAt(i);
    }
    Arrays.sort(a);
    for(int i=0 ; i<3 ; i++){
      if(a[i]=='1'){
        count++;
      }
    }
    System.out.println(count);
  }
} import java.util.*; util.* java public class Main{
  public static void main(String[] args) {
    Scanner sc = new Scanner (System.in);
    String s = sc.next();
    char a[] = new char[3];
    int count = 0;
    for(int i=0 ; i<3 ; i++){
      a[i] = s.charAt(i);
    }
    Arrays.sort(a);
    for(int i=0 ; i<3 ; i++){
      if(a[i]=='1'){
        count++;
      }
    }
    System.out.println(count);
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner (System.in);
    String s = sc.next();
    char a[] = new char[3];
    int count = 0;
    for(int i=0 ; i<3 ; i++){
      a[i] = s.charAt(i);
    }
    Arrays.sort(a);
    for(int i=0 ; i<3 ; i++){
      if(a[i]=='1'){
        count++;
      }
    }
    System.out.println(count);
  } main {
    Scanner sc = new Scanner (System.in);
    String s = sc.next();
    char a[] = new char[3];
    int count = 0;
    for(int i=0 ; i<3 ; i++){
      a[i] = s.charAt(i);
    }
    Arrays.sort(a);
    for(int i=0 ; i<3 ; i++){
      if(a[i]=='1'){
        count++;
      }
    }
    System.out.println(count);
  } Scanner sc = new Scanner (System.in); sc new Scanner (System.in) String s = sc.next(); s sc.next() sc.next sc char a[] = new char[3]; a new char[3] 3 int count = 0; count 0 for(int i=0 ; i<3 ; i++){
      a[i] = s.charAt(i);
    } int i=0 ; int i=0 ; i 0 i<3 i 3 i++ i++ i {
      a[i] = s.charAt(i);
    } {
      a[i] = s.charAt(i);
    } a[i] = s.charAt(i) a[i] a i s.charAt(i) s.charAt s i Arrays.sort(a) Arrays.sort Arrays a for(int i=0 ; i<3 ; i++){
      if(a[i]=='1'){
        count++;
      }
    } int i=0 ; int i=0 ; i 0 i<3 i 3 i++ i++ i {
      if(a[i]=='1'){
        count++;
      }
    } {
      if(a[i]=='1'){
        count++;
      }
    } if(a[i]=='1'){
        count++;
      } a[i]=='1' a[i] a i '1' {
        count++;
      } count++ count System.out.println(count) System.out.println System.out System System.out count String[] args args public class Main{
  public static void main(String[] args) {
    Scanner sc = new Scanner (System.in);
    String s = sc.next();
    char a[] = new char[3];
    int count = 0;
    for(int i=0 ; i<3 ; i++){
      a[i] = s.charAt(i);
    }
    Arrays.sort(a);
    for(int i=0 ; i<3 ; i++){
      if(a[i]=='1'){
        count++;
      }
    }
    System.out.println(count);
  }
} public class Main{
  public static void main(String[] args) {
    Scanner sc = new Scanner (System.in);
    String s = sc.next();
    char a[] = new char[3];
    int count = 0;
    for(int i=0 ; i<3 ; i++){
      a[i] = s.charAt(i);
    }
    Arrays.sort(a);
    for(int i=0 ; i<3 ; i++){
      if(a[i]=='1'){
        count++;
      }
    }
    System.out.println(count);
  }
} Main
import java.util.*;
public class Main{
  public static void main(String[] args) {
    Scanner sc = new Scanner (System.in);
    String s = sc.next();
    char a[] = new char[3];
    int count = 0;
    for(int i=0 ; i<3 ; i++){
      a[i] = s.charAt(i);
    }
    Arrays.sort(a);
    for(int i=0 ; i<3 ; i++){
      if(a[i]=='1'){
        count++;
      }
    }
    System.out.println(count);
  }
}
