Robert

ruudukko = ""
vika = "_"

leveys = input("Pelilaudan leveys? ")
kapeus = input("Pelilaudan kapeus? ")

for i in range(0, leveys):
    for j in range(0, kapeus):
        if (j==0 and i%2==0):
            vika = "_"

        elif (vika == "_"):
            vika = "#"

        else:
            vika = "_"
        ruudukko += vika
    if (i< leveys-1):
        ruudukko += "\n"

print(ruudukko)