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>
#define N 200000
long jud_big(long,long);
long jud_small(long,long);
int main(){
  int i,j,n;
  long minv,maxv,R[N];
  
    scanf("%d",&n);
  for(j=0;j<n;j++)scanf("%ld",&R[j]);
  
maxv = R[1]-R[0];
  minv = R[0];
  for(i=1;i<n;i++){
      maxv = jud_big(maxv,R[i]-minv);
      minv=jud_small(minv,R[i]);
    }
  printf("%ld\n",maxv);
  return 0;
}

long jud_big(long a, long b){
  if(a >= b)return a;
  else return b;
}

long jud_small(long a,long b){
  if(a>=b)return b;
  else return a;
}