Problem:
Score : 100 points

Problem Statement

You went shopping to buy cakes and donuts with X yen (the currency of Japan).

First, you bought one cake for A yen at a cake shop.
Then, you bought as many donuts as possible for B yen each, at a donut shop.

How much do you have left after shopping?

Constraints

1 \leq A, B \leq 1 000

A + B \leq X \leq 10 000

X, A and B are integers.

Input

Input is given from Standard Input in the following format:

X
A
B

Output

Print the amount you have left after shopping.

Sample Input 1

1234
150
100

Sample Output 1

84

You have 1234 - 150 = 1084 yen left after buying a cake.
With this amount, you can buy 10 donuts, after which you have 84 yen left.

Sample Input 2

1000
108
108

Sample Output 2

28

Sample Input 3

579
123
456

Sample Output 3

0

Sample Input 4

7477
549
593

Sample Output 4

405

Solution in Go (1.6) (judge verdict: Accepted)

package main

import(
    "fmt"
)



func main() {
    var x,a,b int
    fmt.Scan(&x,&a,&b)
    ans := (x-a)%b
    fmt.Println(ans)
}





func abs32(a int) int {
    if a<0{
        return -a
    }
    return a
}

func abs64(a int64) int64 {
    if a<0{
        return -a
    }
    return a
}

func min32(a, b int) int {
    if a >= b {
        return b
    }
    return a
}

func max32(a, b int) int {
    if a >= b {
        return a
    }
    return b
}

func min64(a, b int64) int64 {
    if a >= b {
        return b
    }
    return a
}

func max64(a, b int64) int64 {
    if a >= b {
        return a
    }
    return b
}

func gcd(a, b int64) int64 {
    if a % b == 0 {
        return b
    } else {
        return gcd(b, a%b)
    }
}

func lcm(a, b int64) int64 {
    return a / gcd(a, b) * b
}

func scanNums(len int) (nums []int){
    var num int
    for i:=0; i<len; i++{
        fmt.Scan(&num)
        nums = append(nums,num)
    }
    return
}

func scanNums64(len int) (nums []int64){
    var num int64
    for i:=0; i<len; i++{
        fmt.Scan(&num)
        nums = append(nums,num)
    }
    return
}

func scanString(len int) (str []string){
    var s string
    for i:=0; i<len; i++{
        fmt.Scan(&s)
        str = append(str,s)
    }
    return
}

func scanTwoNums(n,m int) ([][]int){
    Nums := make([][]int, n)
    for i:=0; i<n; i++{
        Nums[i] = make([]int, m)
    }
    return Nums
}