Merkkijono

#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

int main() {
	string a;
	getline(cin, a);
	
	auto it = std::adjacent_find(a.begin(), a.end());
	while (true)
	{
		auto it2 = it;
		char b = *it;
		it++;
		int k = 0;
		while (it != a.end())
		{
			if (b != *it)
				break;
			k++;
			it++;
		}
		a.erase(it2, it2+k+1);
		it = std::adjacent_find(a.begin(), a.end());
		if (it == a.end()) break;
	}

	cout << a;
	cin.get();
	cin.get();
}

Test 1

Verdict: RUNTIME ERROR

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED