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(void){
  int n,i,min,max,A;
  int *R;
  while(1){
  scanf("%d",&n);
  if(n>=2 && n<=200000)break;
  }
  R = (int*)malloc(sizeof(int)*n);
  for(i=0 ; i<n ; i++){
    while(1){
      scanf("%d",&R[i]);
      if(R[i]>=1 && R[i]<=1000000000)break;
    }
  }
  min=R[0];
  max=R[1]-min;
  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);
  free(R);
  return 0;
}