#Lutece1106. 红与黑2
红与黑2
Migrated from Lutece 1106 红与黑2
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Description
Iahub and Sorin are the best competitive programmers in their town. However, they can't both qualify to an important contest. The selection will be made with the help of a single problem. Blatnatalag, a friend of Iahub, managed to get hold of the problem before the contest. Because he wants to make sure Iahub will be the one qualified, he tells Iahub the following task.
You're given an (1-based) array a with n elements. Let's define function as . Function g is calculated by the following pseudo-code:
int g(int i, int j) {
int sum = 0;
for (int k = min(i, j) + 1; k <= max(i, j); k = k + 1)
sum = sum + a[k];
return sum;
}
Find a value .
Probably by now Iahub already figured out the solution to this problem. Can you?
Input
The first line of input contains a single integer n. Next line contains n integers a[1], a[2], ..., a[n]
Output
Output a single integer — the value of .
Samples
4
1 0 0 -1
1
Note
20%
100%
Resources
xwind