# Uses python3
import sys

def mergeInversionCount(B, C, D):
    count = 0
    while len(B) != 0 and len(C) != 0:
        b = B[0]
        c = C[0]
        if b <= c:
            D.append(b)
            del B[0]
        else:
            count = count + len(B)
            D.append(c)
            del C[0]
    D.extend(B)
    D.extend(C)
    return count


def getInversionCount(A, D):
    numOfInversions = 0
    if len(A) == 1:
        D.append(A[0])
        return 0
    m = int(len(A) / 2) 
    D1 = []
    numOfInversions = numOfInversions + getInversionCount(A[0:m], D1)
    D2 = []
    numOfInversions = numOfInversions + getInversionCount(A[m:len(A)], D2)
    mergeCount = mergeInversionCount(D1, D2, D)
    return numOfInversions + mergeCount

if __name__ == '__main__':
    input = sys.stdin.read()
    n, *a = list(map(int, input.split()))
    b = n * [0]
    print(getInversionCount(a, b))