1 #include
     
      //by chengdacaizi. 2 #include
      
        3 #define MAXN 25005 4 using namespace std; 5  6 struct Cows  7 { 8     int begin; 9     int end;10 };11 12 Cows cow[MAXN];13 14 int compare(const void * i,const void * j);15 int main()16 {17     //freopen("acm.acm","r",stdin);18     int i;19     int j;20     int n;21     int t;22     bool boo;23     int last;24     int max;25     int tem;26     int max_num;27     int result;28     scanf("%d %d",&n,&t);29     for(i = 0; i < n; ++ i)30     {31         scanf("%d %d",&cow[i].begin,&cow[i].end);32     }33     qsort(cow,n,sizeof(Cows),compare);34     last = 1;35     i = 0;36     max = 0;37     result = 0;38     boo = true;39     while(1)40     {41         max = -1;42         while(cow[i].begin <= last)43         {44             if((tem = cow[i].end - last) > max)45             {46                 max = tem;47                 max_num = i;48             }49             ++ i;50         }51         if(max == -1)52         {53         //    cout<
       
        <<"   000000000000"<
        
         = t)59         {60             break;61         }62         else63         {64             last = cow[max_num].end + 1;65         }66     }67     if(boo)68         cout<
         
          <