#include <cstdio>
#include <ctime>
#include <cstdlib>
using namespace std;

typedef struct _clause {
    int x, y, type;
} Clause;

const int MAX_N = 102;
const int MAX_M = 1002;

int n, m;

Clause clause[MAX_M];
bool assign[MAX_N];

void solve() {
    bool done = false;
    int r;

    while (!done) {
        done = true;
        for (int i = 1; i <= m; ++i) {
            if (clause[i].type == 0) {

                if (!assign[clause[i].x] && !assign[clause[i].y]) {
                    r = rand() % 2;
                    if (r) assign[clause[i].x] = true;
                    else assign[clause[i].y] = true;
                    done = false;
                }
            } else if (clause[i].type == 1) {


                if (!assign[clause[i].x] && assign[clause[i].y]) {
                    assign[clause[i].y] = false;
                    done = false;
                }
            } else if (clause[i].type == 2) {


                if (assign[clause[i].x] && !assign[clause[i].y]) {
                    assign[clause[i].x] = false;
                    done = false;
                }
            } else if (clause[i].type == 2) {

                if (assign[clause[i].x] && assign[clause[i].y]) {
                    rand() % 2 ? assign[clause[i].x] = false
                            : assign[clause[i].y] = false;
                    done = false;
                }
            }
        }
    }
}

int main(int argc, char** argv) {
    freopen("party.in", "r", stdin);
    freopen("party.out", "w", stdout);

    srand(time(NULL));


    scanf("%d %d", &n, &m);
    for (int i = 1; i <= m; i++) {
        scanf("%d %d %d", &clause[i].x, &clause[i].y, &clause[i].type);
    }
    for (int i = 1; i <= n; ++i) assign[i] = rand() % 2;

    solve();
    int vars = 0;
    for (int i = 1; i <= n; ++i) {
        if (assign[i]) {
            vars++;
        }
    }

    printf("%d\n", vars);
    for (int i = 1; i <= n; ++i) {
        if (assign[i]) {
            printf("%d\n", i);
        }
    }
    return 0;
}