gistfile1.java

import java.io.*;
public class solucao{
	public static void main(String[] args)throws IOException{
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int n,k;
		String[] aux;
		n = Integer.parseInt(in.readLine());
		k = 0;
		while(n-- > 0){
			aux = in.readLine().split(" ");	
			if(Integer.parseInt(aux[0]) > Integer.parseInt(aux[1]))
				k += Integer.parseInt(aux[1]);
		}
		System.out.println(k);
    }
}