#include <cstdio>
#include <iostream>
// #include <cstdlib>

const int BLOCK_SIZE = 65536;


#ifdef DEBUG
#define CHECKPOINT { std::cerr << "CHECKPOINT: " << __FILE__ << " (" << __LINE__ << ")" << std::endl; }
#define DEBUGPRINT(x) { std::cerr << "DEBUG: " << __FILE__ << " (" << __LINE__ << "): " << #x << "= " << x << std::endl; }
#else
#define CHECKPOINT
#define DEBUGPRINT(x)
#endif

class UTF8Decoder
{
public:
	enum State {
		ERROR = -1
		, DEFAULT
		, WAITING1
		, WAITING2
		, WAITING3
	};
	UTF8Decoder()
	: state(DEFAULT)
	, codePosition(0)
	, count(0)
	{ }
	State Update(unsigned char ch)
	{
		DEBUGPRINT((unsigned int)ch);
		DEBUGPRINT(state);
		if(state==ERROR)
			return state;
		if(~ch & 0x80)
		{
			if(state==DEFAULT)
			{
				++count;
				codePosition = ch;
				return state;
			}
			return (state = ERROR);
		}
		if((ch & 0x80) && (~ch & 0x40)) // 10xx xxxx
		{
			if(state==WAITING1 || state==WAITING2 || state==WAITING3)
			{
				codePosition = (codePosition << 6) | (ch & 0x3F); // 0x3F = 0011 1111
				return (state = State(static_cast<int>(state)-1));
			}
			return (state = ERROR);
		}
		if(state==DEFAULT)
		{
			++count;
			if((ch & 0xC0) && (~ch & 0x20)) // 110x xxxx
			{
				codePosition = ch & 0x1F; // 0x1F = 0001 1111
				return (state = WAITING1);
			}
			if((ch & 0xE0) && (~ch & 0x10)) // 1110 xxxx
			{
				codePosition = ch & 0x0F; // 0x0F = 0000 1111
				return (state = WAITING2);
			}
			if((ch & 0xF0) && (~ch & 0x08)) // 1111 0xxx
			{
				codePosition = ch & 0x07; // 0x07 = 0000 0111
				return (state = WAITING3);
			}
			--count;
		}
		return (state = ERROR);
	}
	State GetState() const
	{
		return state;
	}
	uint32_t GetCurrent() const
	{
		return codePosition;
	}
	long long GetCount() const
	{
		return count;
	}
	void Reset()
	{
		state = DEFAULT;
		codePosition = 0;
		count = 0;
	}
private:
	State state;
	uint32_t codePosition;
	long long count;
};

int main()
{
	using namespace std;
	
	long long allSize = 0;
	unsigned char buf[BLOCK_SIZE];
	int readedSize;
	
	UTF8Decoder decoder;
	while(true){
		readedSize = fread(buf, 1, BLOCK_SIZE, stdin);
		unsigned char *end = buf + readedSize;
		for(unsigned char *i=buf; i<end; ++i)
		{
			if(decoder.Update(*i)==UTF8Decoder::ERROR)
			{
				DEBUGPRINT(decoder.GetState());
				fprintf(stderr,"Invalid UTF8 character. Char pos: %lld\n",decoder.GetCount());
				return -1;
			}
			if(decoder.GetState()==UTF8Decoder::DEFAULT)
			{
				// printf("%08X\n",decoder.GetCurrent());
				printf("%c",static_cast<char>(decoder.GetCurrent()));
			}
			DEBUGPRINT(decoder.GetState());
		}
		if(readedSize<BLOCK_SIZE)
			break;
	}
	if(decoder.GetState()!=UTF8Decoder::DEFAULT)
	{
		DEBUGPRINT(decoder.GetState());
		fprintf(stderr,"Unfinished UTF8 character. Char pos: %lld\n",decoder.GetCount());
		return -1;
	}
	allSize = decoder.GetCount();
	fprintf(stderr,"Characters found: %lld\n",allSize);
	return 0;
}
# Reason of new version: Corrected stderr semantics.