``
def mod(x):
    if x<0:
        return -x
    else:
        return x

for i in range(rows, -rows-1, -1):
    if i == 0:
        print(int((M-7)/2)*'-' + 'WELCOME' + int((M-7)/2)*'-')
    else:
        print(mod(i)*'---' + (N-2*mod(i))*pin + 
              mod(i)*'---')