Merkkijono

#include <iostream>
#include <string>

using namespace std;

int main()
{
	string str;
	cin >> str;

	for(unsigned int i = 0; i < str.length(); i++)
		if(!isalpha(str[i]))
		{
			str.erase(i, 1);
			i = 0;
		}

	bool loop = true;

	while(loop)
	{
		loop = false;
		for(unsigned int i = 0; i < str.length(); i++)
		{
			char current = str[i];

			unsigned int j = 0;
			for(j = 0; toupper(str[i + j]) == toupper(current); j++);
			if(j > 1)
			{
				str.erase(i, j);
				loop = true;
			}
		}
	}

	for(unsigned int i = 0; i < str.length(); i++)
		cout << (char)toupper(str[i]);
	cout << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: ACCEPTED