#include<fstream>
int MAXH=30;
int s[300000],t[300000],a[300000],b[300000],ne[30][300000],lazy[30][300000],n,tol,head,ans,x;
 
using namespace std;
ifstream fin("boarding.in");
ofstream fout("boarding.out");
void down(int j,int n) {
  if (j==0) 
	  return;
  bool flag=true;
  for(int x=n;x!=ne[j][n];x=ne[j-1][x]){
    if (!flag) 
		a[x]-=lazy[j][n];
    flag=false;
    lazy[j-1][x]+=lazy[j][n];
  }
  lazy[j][n]=0;
}
 
int geth(){
  for(int i=0;i<MAXH;i++){
    if (rand()%2) 
		return i;
  }
  return MAXH; 
}
 
 
bool better(int x, int y) {
  return b[x]-a[x]>=b[y]-a[y];
}
 
int main(){
	fin>>n;
	for(int i=1;i<=n;i++)
		fin>>s[i]>>t[i];
	tol=1;
	for(int i=n;i>=1;i--){
		tol++;
		a[tol]=s[i];
		x=head;
	    for(int j=MAXH;j>=0;--j){
			while (ne[j][x]&&a[ne[j][x]]<a[tol]) 
				x=ne[j][x];
            down(j,x);
        }
		b[tol]=b[x]-a[x]+s[i]+t[i];
		if (b[tol]>ans)
			ans=b[tol];
		x=head; 
		a[x]--;
		for(int j=MAXH;j>=0;--j){
 
			while (ne[j][x]&&a[ne[j][x]]<a[tol]){
				lazy[j][x]++;
                x=ne[j][x];
                a[x]--;
            }
      down(j,x);
 
 
      while (ne[j][x]&&better(tol,ne[j][x])){
        down(j,ne[j][x]);
        ne[j][x] = ne[j][ne[j][x]];
      }
 
	  int height=geth();
      if (height>=j) {
        ne[j][tol]=ne[j][x];
        ne[j][x]=tol;
      }
    }
    a[tol]--;
  }
fout<<ans;
return 0;
}