#include<bits/stdc++.h> using namespace std; int main() { int t,n,i; int a[100],b[100]; cin>>t; while(t--) { int f=0; cin>>n; for(i=0;i<n;i++) { cin>>a[i]>>b[i]; } int max=b[0]-a[0]; for(i=1;i<n;i++) { if(b[i]-a[i]>max) max=b[i]-a[i]; } for(i=0;i<n-1;i++) { if(max>a[i+1]-a[i]) { f=1; break; } } if(f==0) cout<<"YES"<<endl; else cout<<"NO"<<endl; } return 0; } |
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