Day 22 War between odd and even

''' Read input from STDIN. Print your output to STDOUT '''
    #Use input() to read input from STDIN and use print to write your output to STDOUT

def main():
    n = int(input())
    arr = list(map(int,input().split()))
    odd = 0
    even = 0
    for i in range(n):
        if i%2 == 0:
            even += arr[i]
        else:
            odd += arr[i]
    print(abs(even-odd),end='')
    
main()