Problem:
Score : 100 points

Problem Statement

Three poles stand evenly spaced along a line. Their heights are a, b and c meters, from left to right.
We will call the arrangement of the poles beautiful if the tops of the poles lie on the same line, that is, b-a = c-b.

Determine whether the arrangement of the poles is beautiful.

Constraints

1 \leq a,b,c \leq 100

a, b and c are integers.

Input

Input is given from Standard Input in the following format:

a b c

Output

Print YES if the arrangement of the poles is beautiful; print NO otherwise.

Sample Input 1

2 4 6

Sample Output 1

YES

Since 4-2 = 6-4, this arrangement of poles is beautiful.

Sample Input 2

2 5 6

Sample Output 2

NO

Since 5-2 \neq 6-5, this arrangement of poles is not beautiful.

Sample Input 3

3 2 1

Sample Output 3

YES

Since 1-2 = 2-3, this arrangement of poles is beautiful.

Solution in C (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <stdio.h>
#include<string.h>
int main()
{
    char o[50] ,e[50];
  //  printf("Enter the odd position string\n");
   scanf("%s",o);
    //puts(o);
  //   printf("Enter the even position string\n");
    scanf("%s",e);
   // puts(e);
    char pass[100];
    int count=0;
        int count1=0;
    while(o[count]!='\0')
    {
     count++;   
    }
     while(e[count1]!='\0')
    {
    count1++;   
    }
    
 if(count1==count)
 {
    for(int i=0;i<count;i++){
        printf("%c",o[i]);
     printf("%c",e[i]);
       
 
    }
 }
 else if(count>count1)
 {
     for(int i=0;i<count1;i++){
        printf("%c",o[i]);
     printf("%c",e[i]);
       
 
    }
      for(int i=count1;i<count;i++){
        printf("%c",o[i]);
     
       
 
    }
     
 }
    else
    {
        for(int i=0;i<count;i++){
        printf("%c",o[i]);
     printf("%c",e[i]);
       
 
           }
      for(int i=count;i<count1;i++){
        printf("%c",e[i]);
     
       
 
             }
        
    }
     
 
    return 0;
}