Equal Division Byju's Hiring

import java.io.BufferedReader;
import java.io.InputStreamReader;

//import for Scanner and other utility classes
import java.util.*;


// Warning: Printing unwanted or ill-formatted data to output will cause the test cases to fail

class TestClass {
    public static void main(String args[] ) throws Exception {
    
    Scanner sc=new Scanner(System.in);
    int n=sc.nextInt();
    long arr[][]=new long [n][2];
    for(int i=0;i<n;i++)
      {
              long t1=sc.nextLong();
              long t2=sc.nextLong();
              arr[i][0]=t1;
              arr[i][1]=t2;
      }
      long sum=0;
      long add=0;
        for(int i=n-1;i>=0;i--)
        {
           long new_value=add+arr[i][0];
           if(new_value%arr[i][1]!=0)
           {
               long r=new_value/(arr[i][1]);
               r=r+1;
               add=add+(r*arr[i][1]-new_value);
               sum=sum+(r*arr[i][1]-new_value);
           }
           
        }
        System.out.println(sum);
    }
}