C++ :

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int n,m,c,b,ans,f[110000],first[110000],tot;
struct node
{
	int x,y,wgt;
}a[100005];
struct bian
{
	int from,to,next;
}s[100004];
void add(int x,int y)
{
	s[++tot].from=x;
	s[tot].to=y;
	s[tot].next=first[x];
	first[x]=tot;
}
int comp(const node &a,const node &b)
{
	if(a.x==b.x)
		return a.y<b.y;
	return a.x<b.x;
}
int maxc(int a,int b){return a>b?a:b;}
int main()
{
	//freopen("a.in","r",stdin);
	//freopen("a.ans","w",stdout);
	memset(first,-1,sizeof(first));
	scanf("%d",&n);
	m=n,ans=0;
	for(int i=1;i<=n;++i)
	{
		scanf("%d%d",&c,&b);
		a[i].x=c+1,a[i].y=n-b;
		if(a[i].x>a[i].y)//把能直接判断出说谎的去掉
		{
			ans++;
			a[i].x=a[i].y=0x3f3f3f3f;
		}
	}
	sort(a+1,a+n+1,comp);
	n-=ans;
	ans=0;
	//a[1].wgt=1;
	for(int i=1;i<=n;++i)//把排名相同的人化成一个分数段
	{
		a[i].wgt=1;
		if(a[i].x==a[i-1].x&&a[i].y==a[i-1].y)
		{
			a[i].wgt+=a[i-1].wgt;
			a[i-1].x=a[i-1].y=0x3f3f3f3f;
			a[i-1].wgt=0;
			ans++;
			if(a[i].wgt>a[i].y-a[i].x+1)
				a[i].wgt=a[i].y-a[i].x+1;//段中最多的人数
		}
	}
	sort(a+1,a+n+1,comp);
	n-=ans;
	for(int i=1;i<=n;++i)
		add(a[i].y,i);
	for(int i=1;i<=m;++i)
	{
		f[i]=f[i-1];
		for(int j=first[i];j!=-1;j=s[j].next)
		{
			int k=s[j].to;
			f[i]=maxc(f[i],f[a[j].x-1]+a[k].wgt);
		}
	}
	printf("%d",m-f[m]);
//	while(1);
}