#include <stdio.h>

void swap(int *a, int *b)
{
	int temp;
	temp = *a;
	*a = *b;
	*b = temp;
}

void sort(int *s)
{
	if(s[0] > s[1]){
		swap(&s[0], &s[1]);
	}
	if(s[1] > s[2]){
		swap(&s[1], &s[2]);
	}
	if(s[0] > s[1]){
		swap(&s[0], &s[1]);
	}
}

int main(void) {
	int i;
	int a = 0;
	int s[3];
	scanf("%d%d%d", &s[0], &s[1], &s[2]);
	sort(s);
	//printf("%d %d %d:%d\n", s[0], s[1], s[2], a);
	if(s[1] == s[2]){
		printf("%d\n", s[1] / 2 / 2 + s[1] / 2 / 2 + s[0]);
	}
	else{
		printf("%d\n", (s[1] - s[0]) / 2 + (s[2] - s[1]) / 2 / 2 + s[0]);
	}
	
	return 0;
}