#include<iostream>#include<cstdio>#include<string.h>#include<cmath>#include<algorithm>using namespace std;const int MAXN=10100;struct node{int l,p;}fra[MAXN];bool cmp(node x,node y){if (x.p<y.p) return true;else return false;}int main(){int n,i,ans,pre,now;scanf("%d",&n);while (n>0){for (i=0;i<n;i++)scanf("%d%d",&fra[i].l,&fra[i].p);sort(fra,fra+n,cmp);ans=1; pre=0; now=fra[0].p;for (i=1;i<n;i++){if (now<=fra[i].p){ans++; pre=now;if (now+fra[i].l<fra[i].p) now=fra[i].p;else now+=fra[i].l;continue;}if (pre+fra[i].l<now){if (pre+fra[i].l<fra[i].p) now=fra[i].p;else now=pre+fra[i].l;}}printf("%dn",ans);scanf("%d",&n);}return 0;}
