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>

main() {

  int i;
  int n;       //データ数
  int *r;      //データ配列用ポインタ
  int maxv, minv; //最大利益

  scanf("%d", &n);
  
  r = (int *)malloc(sizeof(int) * n);

  for( i=0; i<n; i++) {
    scanf("%d", &r[i]);
  }

  maxv = r[1] - r[0];
  minv = r[0];

  for( i=1; i<n; i++) {
    if(maxv < r[i]-minv) {
      maxv = r[i] - minv;
    }
    if(minv > r[i]) {
      minv = r[i];
    }
  }

  free(r);

  printf("%d\n", maxv);

  return 0;

}