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: Time Limit Exceeded)

#include <stdio.h>
#include <limits.h>
int main(){
  int n;
  int i, j;
  scanf("%d", &n);
  int N[n];
  int R[n-1];
  int max=INT_MIN;
  int tmp;
  for(i=0; i<n; ++i){
	scanf("%d", &N[i]);
  }
  for(i=0; i<(n-1); ++i){
	R[i]=N[i+1]-N[i];
  }
  //sort
  for(i=0; i<(n-1); ++i){
	for(j=(n-1); j>=i+1; --j){
	  tmp=N[j]-N[i];
	  if(max<tmp)
		max=tmp;
	}
  }
  //

  /* for(i=0; i<(n-1); ++i){ */
  /* 	printf("%d ", R[i]); */
  /* } */
  /* printf("\n"); */
  printf("%d\n", max);
  return 0;
}