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>

long long  A[2000001];
long long min,max,d;
int a;

long long make_min(long long x,long long y){
  if(x>=y) min=y;
  else min=x;
  return min;
}
long long make_max(long long x,long long y){
  if(x<=y) max=y;
  else max=x;
  return max;
}

int main(void) {
  scanf("%d",&a);
  for(int i=0;i<a;i++){
      scanf("%d",&A[i]);
  }

  max=A[1]-A[0];
  min = make_min(A[0],A[1]);

    if(a==2){
      max = A[1]-A[0];
    }
      else{
        for(int i=1;i<a;i++){
            d=A[i+1]-min;
            max= make_max(max,d);
            min = make_min(A[i+1],min);
    }
  }

  printf("%d\n",max);

}