题解 | #尼科彻斯定理#

def f(m):
    #公式法
    n=int((m**2-m+2)/2)
    for i in range(m-1):
        print(2*n-1+2*i,end='+')
    print(2*n-1+2*(m-1))
while 1:
    try:
        n=int(input())
        f(n)
    except Exception as e:
        if not isinstance(e,EOFError):
            print('wf_wf__Error')
        break