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 i = 0;
  int num = 0;
  int min = 0;
  int max = 0;
  int *data;

  while(1){
    scanf("%d",&num);
    if(num >= 2 && num <= 200000){
      break;
    }
  }

  data = (int *)malloc(sizeof(int)* num);

  for(i = 0;i < num;i++){
    while(1){
      scanf("%d",&data[i]);
      if(data[i] >= 1 && data[i] <= 1000000000){
        break;
      }
    }
  }

  min = data[0];
  max = data[1] -min;

  for(i = 1;i < num;i++){
    if(max < data[i] - min){
      max = data[i] -min;
    }
    if(min > data[i]){
      min = data[i];
    }
  }
  printf("%d",max);
  printf("\n");
  free(data);
  return 0;
}