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Compress a sensor signal

A field sensor sends a line made of uppercase letters. Compress each consecutive run into its letter followed by the run length. Runs must stay separate when the same letter appears again later.

Input

One line of 1 to 200 uppercase ASCII letters.

Output

One line containing the run-length encoded signal.

Example 1

Input

AAABBCCCCA

Output

A3B2C4A1

Each maximal consecutive run becomes one letter-count pair.

Constraints

1 <= signal length <= 200
Only A through Z appear

Hints

Hint 1 of 3

Start the current run with the first character.

Hint 2 of 3

When the next character changes, append the completed pair.

Hint 3 of 3

Remember to append the final run after the loop.

Solution

Show a reference solution and explanation

Python · reference solution

signal = input().strip()
parts = []
current = signal[0]
count = 1
for char in signal[1:]:
    if char == current:
        count += 1
    else:
        parts.append(current + str(count))
        current = char
        count = 1
parts.append(current + str(count))
print("".join(parts))

JavaScript · reference solution

const signal = readline();
const parts = [];
let current = signal[0];
let count = 1;
for (const char of signal.slice(1)) {
  if (char === current) count++;
  else { parts.push(current + count); current = char; count = 1; }
}
parts.push(current + count);
console.log(parts.join(''));

Approach

The scan keeps the current symbol and its count. A changed symbol closes one run and starts another; because no later change follows the last run, it is emitted once after the loop.