Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

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<limits.h>

int main(){
  int i,buy,value,sell=0,profit=INT_MIN,num,flag=0;
  scanf("%d",&num);
  scanf("%d",&buy);
  for(i=0;i<num-1;i++){
    scanf("%d",&value);
    if(buy > value && i < num-2){
      sell=value;
      if(profit < (sell - buy))profit = sell - buy;
      buy=value;
      sell = 0;
    }
    else if(sell <= value){
      sell=value;
    }
    if(profit < (sell - buy))profit = sell - buy;
  }
  printf("%d\n",profit);
  return 0;
}