diagonal mas

a=[ [0]*5 for i in range(6)]
def print2d(ar):
    for i in range(len(ar)):
        print(" ".join([str(t) for t in ar[i]]))

print2d(a)
num=0
sk=0
for c in range(len(a[0])+len(a)-1):
    sk+=1
    for i in range(len(a)):
        for j in range(len(a[i])):
            if i+j==sk:
                num+=1
                a[i][j]=num

print2d(a)