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 MAX 200000
int max(int a,int b){return a>b ? a: b;}
int min(int a,int b){return a<b ? a: b;}
int main(void){
    int R[MAX],i,n;
    scanf("%d",&n);
    for(i=0;i<n;i++) scanf("%d",&R[i]);
    int maxv=-2000000000;
    int minv=R[0];
    for(int i=1; i<n; i++){
        maxv=max(maxv,R[i]-minv);
        minv=min(minv,R[i]);
    }
    printf("%d\n",maxv);
    return 0;
}