Why am I seeing this output while running this code:

```
list = []
for i in range(4):
    l = int(input())
    list.append(l)

print(str(list))
print("+".join(str(list)))

```

Output:

```
[1, 2, 3, 4]
[+1+,+ +2+,+ +3+,+ +4+]

```

Expected = `[1+2+3+4]`

Please correct my syntax