Problem:
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Maximum Profit

You can obtain profits from foreign exchange margin transactions. For example, if you buy 1000 dollar at a rate of 100 yen per dollar, and sell them at a rate of 108 yen per dollar, you can obtain (108 - 100) × 1000 = 8000 yen.

Write a program which reads values of a currency $R_t$ at a certain time $t$ ($t = 0, 1, 2, ... n-1$), and reports the maximum value of $R_j - R_i$ where $j > i$ .

Input

The first line contains an integer $n$. In the following $n$ lines, $R_t$ ($t = 0, 1, 2, ... n-1$) are given in order.

Output

Print the maximum value in a line.

Constraints

$2 \leq n \leq 200,000$

$1 \leq R_t \leq 10^9$

Sample Input 1

6
5
3
1
3
4
3

Sample Output 1

3

Sample Input 2

3
4
3
2

Sample Output 2

-1

Solution in JAVA (judge verdict: Wrong Answer)


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

class Main{
  public static void main(String args[]) throws IOException{
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

   int n = Integer.parseInt( br.readLine() );

   int[] R = new int[n];

   for(int i = 0; i < n; i++){

	   R[i] = Integer.parseInt( br.readLine() );

   }

   int maxv = R[1] - R[0];
   int minv = R[0];

   for(int j = 1 ; j < n ;j++){

	   if(R[j]-minv > maxv ){
		   maxv = R[j]-minv;
		   System.out.println("maxv= "+maxv);
	   }

	   if(minv > R[j] ){
		   minv = R[j];
		   System.out.println("minv= "+minv);
	   }

   }


   System.out.println(maxv);


 }
}