#include<stdio.h>

int main(void){
    
    int X,Y,Z;
    scanf("%d%d%d",&X,&Y,&Z);
    
    if(X<Y){
        if(X+Z<=Y){
            printf("%d\n",X+Z);   }
        else {
            printf("%d\n",(int)(X+Y+Z)/2);  } }
    
    else  if(X>=Y){
        if(Y+Z<=X){
            printf("%d\n",Y+Z);   }
        else {
            printf("%d\n",(int)(X+Y+Z)/2);  } }
    
    
    return 0;
}