#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
// Yukicoder №91 赤、緑、青の石 ★★
// https://yukicoder.me/problems/no/91
// ***********************
// for debug
#define DEBUGd
// -----------

#define NOP do{}while(0)
#ifdef DEBUG
#include <time.h>
#define TRACE(...) do{printf(__VA_ARGS__);fflush(stdout);}while(0)
#define TRACECR do{putchar_unlocked('\n');fflush(stdout);}while(0)
static clock_t	startclock;
void DEBUGINIT(void){TRACE("--DEBUG MODE --\n");startclock=clock();}
void DEBUGEND(void){startclock=clock()-startclock;TRACE("--finish --\ntime is %.3fms",startclock/1000.);}
#else
#define TRACE(...) NOP
#define TRACECR NOP
void DEBUGINIT(void){return;}
void DEBUGEND(void){return;}
#endif

#define	mypc(d)	putchar_unlocked((int)(d))
#define PRINCR mypc('\n')
#define NOCR(strig) do{char *p;p=strchr(strig,'\n');if(p)*p='\0';}while(0)
// The out-of-date function
#define	asctime(...)	asctime_s(...)
#define	ctime(...)		ctime_s(...)
#define	strlen(a)	mystr_len(a)

// for stdio
#define GETLINE(str) do{char *p;fgets(str,sizeof(str),stdin);p=strchr(str,'\n');if(p)*p='\0';}while(0)
#define mygc(c) (c)=getchar_unlocked()
static char *GETWORD(char* str) {char c;char *cp;cp=&str[0];mygc(c);while(c!=EOF){if((c==' ')||(c=='\n'))break;*cp++=c;mygc(c);}*cp='\0';return &str[0];}
#define	GETINTS(a,b) {char s[34];int *ap=a;REP(i,b){GETWORD(s);*ap++=atoi(s);}}
static int GETLINEINT(void) {char s[34];GETLINE(s);return atoi(s);}
static int GETWORDINT(void) {char s[34];GETWORD(s);return atoi(s);}
static long GETWORDLONG(void) {char s[34];GETWORD(s);return atol(s);}
static int maxi(int a,int b){if((a)>(b)){return a;}return b;}
static long maxl(long a,long b){if(a>b){return a;}return b;}
#define SWAP(type,a,b) do{type _c;_c=a;a=b;b=_c;}while(0)
#define MAX(a,b)	((a)>(b)?(a):(b))
#define MIN(a,b)	((a)<(b)?(a):(b))
#define REP(a,b) for(int a=0;a<(int)(b);++a)
#define REP1(a,b) for(int a=1;a<=(int)(b);++a)
#define Possible(a) 	   printf("%s",((a)?"Possible":"Impossible"))
#define possible(a) 	   printf("%s",((a)?"possible":"impossible"))

// *********************
// *********************
int	stone[3];
// *********************
#define	a	stone[0]
#define	b	stone[1]
#define	c	stone[2]
int main( void ) {
	int	sa;
	int	bi,si;

	DEBUGINIT();
	REP(i,3){
		stone[i] = GETWORDINT();
	}
	if( a >= c && b >= c ) {
		si = 2;
	} else if( a >= b && c >= b ) {
		si = 1;
	} else {
		si = 0;
	}
	if( a >= c && a >= b ) {
		bi = 0;
	} else if( b >= a && b >= c ) {
		bi = 1;
	} else {
		bi = 2;
	}
	sa = stone[bi] - stone[si];
	TRACE("%d %d %d\n",a,b,c);
	while( sa > 1 ) {
		stone[si]++;
		stone[bi] -= 2;
		TRACE("%d %d %d\n",a,b,c);
		if( a >= c && b >= c ) {
			si = 2;
		} else if( a >= b && c >= b ) {
			si = 1;
		} else {
			si = 0;
		}
		if( a >= c && a >= b ) {
			bi = 0;
		} else if( b >= a && b >= c ) {
			bi = 1;
		} else {
			bi = 2;
		}
		sa = stone[bi] - stone[si];
	}
	printf("%d\n",MIN(a,MIN(b,c)));
	DEBUGEND();
}