问题标题: 酷町堂：2624 40分 求找错

#include<iostream>
#include<string>
#include<cstdio>
#include<algorithm>
using namespace std;
int n,c,st1=-1,st2=-1;
struct f{
    int x,y;
}a[10010];
bool cmp(f a,f b){
    if(a.y!=b.y)
        return a.y<b.y;
    return a.x<b.x;
}
int main(){
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>a[i].x>>a[i].y;
    sort(a+1,a+n+1,cmp);
    for(int i=1;i<=n;i++){
        if(a[i].x<st1){
            if(a[i].x>=st2){
                st2=a[i].y;
                c++;
            }
        }else{
            st1=a[i].y;
            c++;
        }
    }
    cout<<c+1;
    return 0;
}