#include<cstdio> #include<cstring> #include<algorithm> using namespace std; struct node { int x,y; }p[50001]; int cmp(node a,node b) { if(a.x!=b.x) return a.x<b.x; else return a.y<b.y; } int main() { //freopen("a.txt","r",stdin); int n,i,j,maxn=0; scanf("%d",&n); for(i=0;i<n;i++) scanf("%d%d",&p[i].x,&p[i].y); sort(p,p+n,cmp); int m=p[0].y; for(i=1;i<n;i++) { if(p[i].y>=m) { maxn=max(maxn,m-p[i].x); m=p[i].y;} else maxn=max(maxn,p[i].y-p[i].x); } printf("%d ",maxn); return 0; }