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>
#define N 200000
int max(int, int);
int min(int, int);

int main(){
  int i, j, n, R[N], maxv, minv;
  scanf("%d",&n);
  if(n < 2 || n > N)exit(1);
  for(i = 0; i <= n - 1; i++){
    scanf("%d",&R[i]);
    if(R[i] < 1 || R[i] > 10*10*10*10*10*10*10*10*10)exit(2);
  }
  minv = R[0];
  maxv = R[1] - R[0];
  for(j = 1; j <= n - 1; j++){
    maxv = max(maxv, R[j] - minv);
    minv = min(minv, R[j]);
  }
  printf("%d\n",maxv);
  return 0;
}

int max(int maxv, int R1){
  if(maxv > R1)return maxv;
  else return R1;
}

int min(int minv, int R2){
  if(minv < R2)return minv;
  else return R2;
}