#include <cstdio>
 
const int INF = 10000000;
 
int N, M;
int S, E;
 
int data[203][203];
 
int main() {
    scanf("%d %d", &N, &M);
 
    for (int i = 1; i <= N; i ++) {
        for (int j = 1; j <= N; j ++) {
            data[i][j] = INF;
        }
        data[i][i] = 0;
    }
 
    while (M --) {
        int a, b, c;
        scanf("%d %d %d", &a, &b, &c);
        if (data[a][b] > c) {
            data[a][b] = c;
        }
    }
 
    scanf("%d %d", &S, &E);
 
    for (int k = 1; k <= N; k ++) {
        for (int i = 1; i <= N; i ++) {
            for (int j = 1; j <= N; j ++) {
                if (data[i][j] > data[i][k] + data[k][j]) {
                    data[i][j] = data[i][k] + data[k][j];
                }
            }
        }
    }
 
    int cnt = 0;
    for (int i = 1; i <= N; i ++) {
        if (data[S][i] + data[i][E] == data[S][E]) {
            cnt ++;
        }
    }
 
    printf("%d\n", cnt);
    for (int i = 1; i <= N; i ++) {
        if (data[S][i] + data[i][E] == data[S][E]) {
            printf("%d\n", i);
        }
    }
    return 0;
}

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4 4
1 3 1
3 4 1
1 2 1
2 4 1
1 4