Sign change

Problem to change the sign in given string. The sign "+ or -" only.

Example-1:

Input    : S = "+21--"
Output   : -21++

Example-2:

Input    : S = "21"
Output   : 21

Solution

n = "+21--"

d = ""

for x in n:

    if(x=="+"):

        d += "-"

    elif(x == "-"):

        d += "+"

    else:

        d += x

print(d)

Output

-21++