import java.util.Scanner;

public class No920 {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    
    int redBall = sc.nextInt();
    int blueBall = sc.nextInt();
    int whiteBall = sc.nextInt();
    int purpleBall = 0 ;

    while(whiteBall > 0){
      if((redBall + blueBall) > 0){
        if(redBall < blueBall){
          whiteBall--;
          redBall++;
        }else if (redBall > blueBall){
          whiteBall--;
          blueBall++;
        }else {
          if(whiteBall < 2){
          break;
          }else{
            whiteBall -= 2;
            blueBall++;
            redBall++;
          }
        }
      }
    }
    while(redBall > 0 && blueBall > 0){
      redBall--;
      blueBall--;
      purpleBall++;
    }
    sc.close();
    System.out.println(purpleBall);
  }
}