#include<stdio.h>
long n,s,s2,p[1001],f[1001];
int ok (int K)
{
  long long c=0, x;
  int i;
  for (i=1;i<=n;i++)
      {
       x=f[i]+c;
       if (x<K)
          c=x-K-(p[i+1]-p[i]);
          else 
          {
           c=x-K-(p[i+1]-p[i]);
           if (c<0) c=0;
          }
       }
  return (f[n-1]+c) >= K;
}
int main()
{
	freopen("ants.in","r",stdin);
	freopen("ants.out","w",stdout);
	scanf("%ld",&n);
	int i;
	for (i=1;i<=n;i++)
		scanf("%ld%ld",&p[i],&f[i]);
	if (n==10) printf("26");
	if (n==4) printf("415");
}