Codeforces807 B. T-Shirt Hunt 2017-05-08 23:23 175人阅读 评论(0) 收藏

B. T-Shirt Hunt

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

Not so long ago the Codecraft-17 contest was held on Codeforces. The top 25 participants, and additionally random 25 participants out of those who got into top 500, will receive a Codeforces T-shirt.

Unfortunately, you didn't manage to get into top 25, but you got into top 500, taking place p.

Now the elimination round of 8VC Venture Cup 2017 is being held. It has been announced that the Codecraft-17 T-shirt winners will be chosen as follows. Let s be
the number of points of the winner of the elimination round of 8VC Venture Cup 2017. Then the following pseudocode will be executed:

i := (s div 50) mod 475
repeat 25 times:
    i := (i * 96 + 42) mod 475
    print (26 + i)

Here "div" is the integer division operator, "mod" is the
modulo (the remainder of division) operator.

As the result of pseudocode execution, 25 integers between 26 and 500, inclusive, will be printed. These will be the numbers of places of the participants who get the Codecraft-17 T-shirts. It is guaranteed that the 25 printed integers will be pairwise distinct
for any value of s.

You're in the lead of the elimination round of 8VC Venture Cup 2017, having x points. You believe that having at least y points
in the current round will be enough for victory.

To change your final score, you can make any number of successful and unsuccessful hacks. A successful hack brings you 100 points, an unsuccessful one takes 50 points from you. It's difficult to do successful hacks, though.

You want to win the current round and, at the same time, ensure getting a Codecraft-17 T-shirt. What is the smallest number of successful hacks you have to do to achieve that?

Input

The only line contains three integers p, x and y (26 ≤ p ≤ 500; 1 ≤ y ≤ x ≤ 20000) —
your place in Codecraft-17, your current score in the elimination round of 8VC Venture Cup 2017, and the smallest number of points you consider sufficient for winning the current round.

Output

Output a single integer — the smallest number of successful hacks you have to do in order to both win the elimination round of 8VC Venture Cup 2017 and ensure getting a Codecraft-17 T-shirt.

It's guaranteed that your goal is achievable for any valid input data.

Examples

input

239 10880 9889

output

0

input

26 7258 6123

output

2

input

493 8000 8000

output

24

input

101 6800 6500

output

0

input

329 19913 19900

output

8

Note

In the first example, there is no need to do any hacks since 10880 points already bring the T-shirt to the 239-th place of Codecraft-17 (that is, you). In this case, according to the pseudocode, the T-shirts will be given to the participants at the following
places:

475 422 84 411 453 210 157 294 146 188 420 367 29 356 398 155 102 239 91 133 365 312 449 301 343

In the second example, you have to do two successful and one unsuccessful hack to make your score equal to 7408.

In the third example, you need to do as many as 24 successful hacks to make your score equal to 10400.

In the fourth example, it's sufficient to do 6 unsuccessful hacks (and no successful ones) to make your score equal to 6500, which is just enough for winning the current round and also getting the T-shirt.

——————————————————————————————————————

题目的意思是给出一个人的位置和他的分数和能获得第一的分数，hack成功一发+100

分，失败一发-50分，求他拿第一且领到衣服至少要成功多少发（失败不算），拿衣服的

位置有他的分数经伪代码处理得到

思路：先算出拿第一至少要拿多少分，在判断只失败能否达成条件，若不能则每次加50

分（+50和+100都是一次hack），直到可以位置

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>
#include <cmath>
#include <set>
#include <stack>
#include <queue>
#include <vector>
#include <bitset>
#include <functional>

using namespace std;

#define LL long long
const int INF=0x3f3f3f3f;
int p,x,y;

bool ok(int n)
{
  int s=(n/50)%475;
  for(int i=0;i<25;i++)
  {
      s=(s*96+42)%475;
      if(s+26==p)
        return 1;
  }
    return 0;
}

int main()
{

    scanf("%d%d%d",&p,&x,&y);
    int ans=0;
    if(x<y)
        ans+=(y-x+99)/100;
    x+=ans*100;
    int xx=x;
    while(xx>=y)
    {
        if(ok(xx))
        {
            printf("%d\n",ans);
        return 0;
        }
        xx-=50;
    }

    int cnt=0;
    while(1)
    {
        if(ok(x+cnt*50))
        {
            break;
        }
        cnt++;
    }
    ans=ans+(cnt+1)/2;
    printf("%d\n",ans);
    return 0;
}