#include "hipermetropie.h"
#include <iostream>
#include <algorithm>
#include <vector>

int main(){
    int n, m; std::cin >> n >> m;
    
    std::vector<int> u(m), v(m);
    
    for(int i = 0; i < m; i++)
        std::cin >> u[i] >> v[i];

    auto[days, people] = solve(n, std::move(u), std::move(v));

    std::string answer(n, '0');
    for(int person : people) {
    	if (!(1 <= person && person <= n)) {
    		std::cerr << "Indexul supusului este invalid" << std::endl;
    		return 0;
    	} else if (answer[person - 1] == '1') {
    		std::cerr << "Supus duplicat" << std::endl;
    		return 0;
    	}
        answer[person - 1] = '1';
    }

    std::cout << days << '\n' << answer << '\n'; 
}