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: Time Limit Exceeded)

#include<stdio.h>

int main() {
  int n,R[200000],minv,maxv,j;
   while(1) {
  scanf("%d",&n);
    if(2 > n || n > 200000) continue;
   }
  for(j = 0;j < n;j++) {
    scanf("%d",&R[j]);
    if(1 > R[j] || R[j] > 1000*1000*1000) j=j-1;
  }
  maxv = R[1]-R[0];
  minv = R[0];
  
  for(j=1;j<=n-1;j++) {
    if(maxv > R[j]-minv) maxv = maxv;
    else maxv = R[j]-minv;
    if(minv < R[j]) minv =minv;
    else minv = R[j];
  }
  printf("%d\n",maxv);
  return 0;
}