Description
N個矩形,排成一排. 現在希望用盡量少的矩形海報Cover住它們.

Input
第一行給出數字N,代表有N個矩形.N在[1,250000] 下面N行,每行給出矩形的長與寬.其值在[1,1000000000]2 1/2 Postering

Output
最少數量的海報數.

Sample Input
5
1 2
1 3
2 2
2 5
1 4

Sample Output
4

HINT

單調遞增棧隨便搞一下，水題一個

/*program from Wolfycz*/
#include<cmath>
#include<cstdio>
#include<cstring>
#include<iostream>
 

#include<algorithm>
#define inf 0x7f7f7f7f
using namespace std;
typedef long long ll;
typedef unsigned int ui;
typedef unsigned long long ull;
inline int read(){
    int x=0,f=1;char ch=getchar();
    for (;ch<‘0‘||ch>‘9‘;ch=getchar())  if (ch==‘-‘)    f=-1;
    for (;ch>=‘0‘&&ch<=‘9‘
 
;ch=getchar())    x=(x<<1)+(x<<3)+ch-‘0‘;
    return x*f;
}
inline void print(int x){
    if (x>=10)     print(x/10);
    putchar(x%10+‘0‘);
}
const int N=2.5e5;
int stack[N+10],top;
int main(){
    int n=read(),same=0;
    for (int i=1;i<=n;i++){
        int x=read(),y=read();
        while
 
 (top&&y<=stack[top]){
            if (y==stack[top])  same++;
            top--;
        }
        stack[++top]=y;
    }
    printf("%d\n",n-same);
    return 0;
}

[Poi2008]海報PLA