Codeforces Round #495 (Div. 2) B

题目链接：http://codeforces.com/contest/1004/problem/B

B. Sonya and Exhibition

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Sonya decided to organize an exhibition of flowers. Since the girl likes only roses and lilies, she decided that only these two kinds of flowers should be in this exhibition.

There are $\mathrm{nn flowers\; in\; a\; row\; in\; the\; exhibition.\; Sonya\; can\; put\; either\; a\; rose\; or\; a\; lily\; in\; the ii-th\; position.\; Thus\; each\; of nn positions\; should\; contain\; exactly\; one\; flower:\; a\; rose\; or\; a\; lily.}$

She knows that exactly $\mathrm{mm people\; will\; visit\; this\; exhibition.\; The ii-th\; visitor\; will\; visit\; all\; flowers\; from lili to riri inclusive.\; The\; girl\; knows\; that\; each\; segment\; has\; its\; own beauty that\; is\; equal\; to\; the\; product\; of\; the\; number\; of\; roses\; and\; the\; number\; of\; lilies.}$

Sonya wants her exhibition to be liked by a lot of people. That is why she wants to put the flowers in such way that the sum of beauties of all segments would be maximum possible.

Input

The first line contains two integers $\mathrm{nn and mm (1\le n,m\le 1031\le n,m\le 103) —\; the\; number\; of\; flowers\; and\; visitors\; respectively.}$

Each of the next $\mathrm{mm lines\; contains\; two\; integers lili and riri (1\le li\le ri\le n1\le li\le ri\le n),\; meaning\; that ii-th\; visitor\; will\; visit\; all\; flowers\; from lili to ririinclusive.}$

Output

Print the string of $\mathrm{nn characters.\; The ii-th\; symbol\; should\; be\; «0»\; if\; you\; want\; to\; put\; a\; rose\; in\; the ii-th\; position,\; otherwise\; «1»\; if\; you\; want\; to\; put\; a\; lily.}$

If there are multiple answers, print any.

Examples

input

Copy

5 3
1 3
2 4
2 5

output

Copy

01100

input

Copy

6 3
5 6
1 4
4 6

output

Copy

110010

Note

In the first example, Sonya can put roses in the first, fourth, and fifth positions, and lilies in the second and third positions;

• in the segment $[1\dots 3][1\dots 3],\; there\; are\; one\; rose\; and\; two\; lilies,\; so\; the beauty is\; equal\; to 1\cdot 2=21\cdot 2=2;$
• in the segment $[2\dots 4][2\dots 4],\; there\; are\; one\; rose\; and\; two\; lilies,\; so\; the beauty is\; equal\; to 1\cdot 2=21\cdot 2=2;$
• in the segment $[2\dots 5][2\dots 5],\; there\; are\; two\; roses\; and\; two\; lilies,\; so\; the beauty is\; equal\; to 2\cdot 2=42\cdot 2=4.$

The total beauty is equal to $\mathrm{2+2+4=82+2+4=8.}$

In the second example, Sonya can put roses in the third, fourth, and sixth positions, and lilies in the first, second, and fifth positions;

• in the segment $[5\dots 6][5\dots 6],\; there\; are\; one\; rose\; and\; one\; lily,\; so\; the beauty is\; equal\; to 1\cdot 1=11\cdot 1=1;$
• in the segment $[1\dots 4][1\dots 4],\; there\; are\; two\; roses\; and\; two\; lilies,\; so\; the beauty is\; equal\; to 2\cdot 2=42\cdot 2=4;$
• in the segment $[4\dots 6][4\dots 6],\; there\; are\; two\; roses\; and\; one\; lily,\; so\; the beauty is\; equal\; to 2\cdot 1=22\cdot 1=2.$

The total beauty is equal to $\mathrm{1+4+2=71+4+2=7.}$

题意： 给出一个n朵花，m个游客的访问区间，它可以在每个位置放0或1 ，然后它有一个漂亮程度的方法，在给定的区间里面，0的个数乘以1的个数就是他的漂亮程度，求怎么摆放0 1才能使漂亮程度最高

思路：她给了m个区间，想想一个区间内怎么才能使值是最大的，无非就是0取一半1取一半，这个是肯定得，自己推一个例子就想得到，然后我们就可以进行下一步，要使每个区间得0 1数量各取一半

首先这是一个构造题，答案不唯一，所以一般这种题都是一些考思维性的，一种固定的构造方法，我开始也是去想怎么合并区间，然后发现还是会有影响其他区间的01数，最后仔细的想了下，我无非就是

要每个区间的01数各一半，而且又不影响其他其他区间，我们就可以>V< 010101,这种岔开的排列无论哪个区间肯定会各取一半，这个算是一个思维好题

#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
struct sss
{
    int left,right;
}a[1001];
int main()
{
    int n,m;
    char str[1001];
    scanf("%d%d",&n,&m);
    int l,r;
    for(int i=0;i<m;i++)
    {
        scanf("%d%d",&a[i].left,&a[i].right);
    }
    for(int i=0;i<n;i++)
    {
        if(i%2) str[i]='1';
        else str[i]='0';
    }
    str[n]='';
    printf("%s",str);
}