def trim(s):

    [i, j ] = [0, len(s)-1]

    while(i<=j and s[i] == ' '): i +=1

    while (j>=i and s[j] == ' '): j -= 1

    return '' if j<i else s[i:j+1]

def trim(s):

    i,j=0,len(s)-1

    while s[i]==" " and i<=j:

        i+=1

    while s[j]==" " and j>=0:

        j-=1

    if i!=j:

        return s[i:j]

    else:

        return s[i]