#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(){
   int a,b,c,ans;
   scanf("%d %d %d",&a,&b,&c);
   if(((a < b)||(c < b))&&(a != b)&&(b != c)){
      //printf("%d\n",b-a);
      if(a < c){
         ans = b-c;
         if(ans > b-c+1)ans = b-c+1;
      }else {
         ans = b-a;
         if(ans > b-a+1)ans = b-a+1;
      }
   }
   if(ans < 0)ans = 0;
   printf("%d\n",ans);
}