text: class Solution:
      def uniquePaths(self, m: int, n: int) -> int:
          m,n = m-1,n-1
          a,b = m,n
          if m>n:
              a=m
              b=n
          else:
              a=n
              b=m
          s=a+b
          nu,de = 1,1
          while(b>0):
              nu*=s
              de*=b
              s-=1
              b-=1
          return int(nu/de)
          
  