import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        try (Scanner scan = new Scanner(System.in)) {
            int v[] = new int[3];
            v[0] = Integer.parseInt(scan.next());
            v[1] = Integer.parseInt(scan.next());
            v[2] = Integer.parseInt(scan.next());
            
            while(true) {
                if(v[0] == v[1] && v[0] == v[2]) {
                    System.out.println(v[0]);
                    return;
                }
                
                int maxI = 0;
                int minI = 0;
                int max = v[maxI];
                int min = v[minI];
                for(int i=1; i<3; i++) {
                    if(max < v[i]) {
                        max = v[i];
                        maxI = i;
                    }
                    if(min > v[i]) {
                        min = v[i];
                        minI = i;
                    }
                }
                
                if(max - min == 1) {
                    System.out.println(min);
                    return;
                }
                
                v[maxI] -= 2;
                v[minI] += 1;
            }
        }
    }
}