CodeForces 675 A Infinite Sequence

A. Infinite Sequence
Time Limit:1000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u
Submit Status Practice CodeForces
675A

Description

Vasya likes everything infinite. Now he is studying the properties of a sequence s, such that its first element is equal to a (s1 = a),
and the difference between any two neighbouring elements is equal to c (si - si - 1 = c).
In particular, Vasya wonders if his favourite integer bappears in this sequence, that is, there exists a positive integer i, such
that si = b. Of course, you are the person he asks for a help.

Input

The first line of the input contain three integers a, b and c ( - 109 ≤ a, b, c ≤ 109) —
the first element of the sequence, Vasya's favorite number and the difference between any two neighbouring elements of the sequence, respectively.

Output

If b appears in the sequence s print "YES" (without quotes), otherwise print "NO"
(without quotes).

Sample Input

Input

1 7 3

Output

YES

Input

10 10 0

Output

YES

Input

1 -4 5

Output

NO

Input

0 60 50

Output

NO

思路：利用等差数列第n项公式，An=A1+（n-1）* d   即可。
AC代码:

#include<stdio.h>
int main()
{
long long a,b,c;
while(scanf("%lld%lld%lld",&a,&b,&c)!=EOF)
{
long long k=0,l=0;
if(c==0)
{
if(a==b)
printf("YES\n");
else
printf("NO\n");
}
else
{
k=(b-a)/c;
l=(b-a)%c;
if(l==0&&k>=0)
printf("YES\n");
else
printf("NO\n");
}
}
return 0;
}