Python :

import math
import sys
n,r=list(map(int,input().split()))

vis=[0]*(n+1)
a=[0]*(n+1)

def df(step):
    if step>r:
        for item in a[1:1+r]:
            print(item,end=" ")
        print()
        return 
    for i in range(1,n+1):
        if vis[i]==0:
            a[step]=i
            vis[i]=1
            df(step+1)
            vis[i]=0
df(1)