#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <math.h>
int main(void)
{
    long long int suburicnt=0,yasumi1,yasumi2,day;
    scanf("%lld %lld %lld",&yasumi1,&yasumi2,&day);
    if(day>yasumi1&&day>yasumi2)
    {
        suburicnt=day-2;
    }
    else if (day<yasumi1||day<yasumi2)
    {
        suburicnt=day-1;
    }
    else
    {
        day=suburicnt;
    }
    if(suburicnt<0)
    {
        suburicnt=0;
    }
    printf("%lld",suburicnt);
}