Fibonaci Closest Number

//   Fibonacci Closest Number
//   Simeon Baltadziev
//   30.04.2017
//   C programming basics
//   WIP

#include <stdio.h>

int main (int argc, char *argv[])
{
    int i;
    int j;
    long  arrayNumber[40];
    long  difference = 10;
    long  minDifference = 100000;
    long  number = 0;
    //long  currentNumber;

    long long enteredNumber = 0;
    printf("Enter fibonacci number: ");
    scanf("%ld", &enteredNumber);
    // Checks if input value is 0 or negative number
    if(enteredNumber == 0) { printf("Error: Input larger number than 0"); }
    if(enteredNumber <0)   { printf("Error: Input possitive number"); }
    long long a = 1, b =1; // Declaring the fisrt two fibonacci numbers
      for(i = 0; i<=40;i++) {
        // Fibonacci Number Formula
        b = a-b;
        a = a+b;
        arrayNumber[i] = b;
        //prlong long f("%d\n", b);

        }

      for(j = 0; j<=40; j++) {
    long long  diff = 0;
              long long  diff2 = 0;
              if(enteredNumber > arrayNumber[j] && enteredNumber < arrayNumber[j+1]) {
       //prlong long f("number 1 and two %d,%d\n", arrayNumber[j], arrayNumber[j+1]);

              diff =  enteredNumber - arrayNumber[j];
              diff2 = enteredNumber - arrayNumber[j+1];
              if (diff < 0) { diff = diff*(-1); }
              if (diff2< 0) { diff2 = diff2*(-1);}
              if (diff<diff2) { minDifference = diff; number = j;}
              if (diff2<diff) { minDifference = diff2; number = j+1;}
              //prlong long f("diff1 and 2 %d, %d\n", diff,diff2);
              }

        }

   // if(enteredNumber>0) {
    //prlong long f("The difference is %ld\n", minDifference);
    printf("The closest number is: %ld\n", number);
   printf("The closest number is: %ld", arrayNumber[number]);
     // }
      //printf("%d", arrayNumber[20]);


    return 0;
    }