Digit Histogram from Input

Write a program that reads non-negative integers from standard input until the input ends. Count how many times each decimal digit 0 to 9 appears across all the numbers, using an array<int, 10> where index d holds the count for digit d. The number 0 itself contributes one digit 0.

Print one line for each digit whose count is greater than zero, in increasing digit order: the digit, a colon, a space, and the count. Digits that never appeared are not printed at all.

Example input:
12 13

The output for that input is shown in Expected Output.