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>

int main(void){
	
	int n;
	
	scanf("%d", &n);
	
	int r[n], t;
	
	for(t=0; t<n; t++){
		scanf("%d", &r[t]);
	}
	
	int i, j, maxv=-999999999, minv=r[0];
	
	for(j=1; j<n; j++){
		
		if(maxv < r[j]-minv){
			maxv = r[j]-minv;
		}
		
		if(r[j] < minv){
			minv = r[j];
		}
	}
	
	
	/*for(i=0; i<n; i++){	
		
		if(max < max+r[i]){
			max=max+r[i];
		}
		
		if(max < r[i+1]-r[i]){
			max=r[i+1]-r[i];
		}	
	}*/
	
	
	printf("%d\n", maxv);
	return 0;
	
}