I have this python program that adds strings to integers:

```
a = raw_input("Enter a: ")
b = raw_input("Enter b: ")
print "a + b as strings: " + a + b
a = int(a)
b = int(b)
c = a + b
str(c)
print "a + b as integers: " + c

```

I get this error:

```
TypeError: cannot concatenate 'str' and 'int' objects

```

How can I add strings to integers?