import sys
sys.setrecursionlimit(100000000)
input = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = 10 ** 15

class BinaryIndexedTree():

    def __init__(self,init_val):
        self.bit = [0] + init_val
        self.n  = len(init_val)

    def sum(self,i):
        ret = 0
        while i > 0:
            ret += self.bit[i]
            i -= (i & -i)
        return ret
    
    def add(self,i,x):
        while i <= self.n:
            self.bit[i] += x
            i += (i & -i)

def main():
    N = int(input())
    M = [int(input()) for _ in range(N)]

    bit = BinaryIndexedTree([0] * N)
    ans = 0
    for i,m in enumerate(M):
        ans += i - bit.sum(m)
        bit.add(m,1)
    print(ans)
if __name__ == '__main__':
    main()