import sys
input = sys.stdin.buffer.readline

def main():
    N = int(input()); INF = pow(10,18)
    P = list(map(int,input().split()))
    ans = 0
    for i in range(N):
        if P[i] == N:
            ans -= (i+1)
        else:
            ans += (i+1)
    ans = max(ans, 0)
    print(ans)


if __name__ == '__main__':
    main()