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>
#include <time.h>

int main(void){
  int i,j,n,min,max,get,*rate;
  //?????????
  scanf("%d",&n);
  rate=(int *)malloc(sizeof(int)*n);
  for(i=0;i<n;i++)
    scanf("%d",&rate[i]);
  min=rate[n-1];
  max=rate[n-1];
  get=-2000000000;//????°?????????±

  //??????:??????????????????
  for(i=n-2;0<=i;i--){
    if(min>rate[i+1])
      min=rate[i+1];
    if(max<rate[i+1])
      max=rate[i+1];
    if(get<max-rate[i])
      get=max-rate[i];
  }
  printf("%d\n",get);
  
  //??????
  free(rate);
  return(0);
}