Helpful Maths

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Problem statement

An addition expression contains only the single-digit values 1, 2 and 3, separated by plus signs. Rearrange its terms into nondecreasing order without changing any term or adding spaces. Output the reordered expression.

Input format

One line containing the expression.

Output format

Print the sorted expression using + separators.

Constraints

1 <= expression length <= 100; expression is valid.

Sample input

3+1+2+1

Sample output

1+1+2+3