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: Time Limit Exceeded)

#include<stdio.h>
#include<stdlib.h>
#define max(a,b) (a>b?a:b)
#define mini -1000000008

typedef struct value {
    //int n[200000];
    int max;
    int R;
} Value;

int main(){
    int i, j;
    Value *value;
    int n;
    int r;
    int ma;
    int diff;

    scanf("%d", &n);
    value = calloc(n, sizeof(Value));

    for(i=0;i<n;i++){
        scanf("%d",&value[i].R);
        ma = mini;
        for(j=0;j<i;j++){
            //value[i].n[j]=value[i].R-value[j].R;
            diff=value[i].R-value[j].R;
            ma = max(diff, ma);
        }
        value[i].max = ma;
    }
    ma = mini;
    for(i=0;i<n;i++){
        ma = max(ma, value[i].max);
    }
    printf("%d\n", ma);

    return 0;
}