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 C (judge verdict: Accepted)

#include<stdio.h>
#include<stdlib.h>

int main(){
  int n, i, max=-1000000000, min;
  int R[200000];

  scanf("%d",&n);
  if( n<2 || 200000<n ) exit(1);

  min = R[0];
  for( i=0 ; i<n ; i++ ){
    scanf("%d",&R[i]);
    if( R[i]<1 || 1000000000<R[i] ) exit(1);
  }

  min = R[0];
  
  for( i=1 ; i<n ; i++ ){
    if( max < R[i]-min ){
      max = R[i] - min;
    }

    if( min > R[i] ){
      min = R[i];
    }
  }

  printf("%d\n",max);
  return 0;
}