vvvv

#include <fstream>
#include <string>

using namespace std;

ifstream in("input.txt");
ofstream out("output.txt");

int encode_bytes_num(int char_code) {
    if (char_code >= (1 << 16)) {
        return 4;
    } else if (char_code >= (1 << 11)) {
        return 3;
    } else if (char_code >= (1 << 7)) {
        return 2;
    } else {
        return 1;
    }
}

/*
 1000 0000 - 80
 1100 0000 - C0
 1110 0000 - E0
 1111 0000 - F0

 7  - 0xxxxxxx
 11 - 110xxxxx 10xxxxxx
 16 - 1110xxxx 10xxxxxx 10xxxxxx
 21 - 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
 */

// encodes char with binary 'char_code' to utf-8 character
string encode(int char_code) {
    int byte_cnt = encode_bytes_num(char_code);

    int first_byte[] = {0, 0, 0xC0, 0xE0, 0xF0};

    int code[4];

    code[0] = first_byte[byte_cnt];
    for (int byte = byte_cnt - 1; byte >= 1; --byte) {
        code[byte] = 0x80 + char_code % (1 << 6);
        char_code >>= 6;
    }

    code[0] += char_code;
    return string(code, code + byte_cnt);
}

int main() {
    int char_code;
    in >> char_code;
    while (in >> char_code) {
        out << encode(char_code);
    }
}