#include<stdio.h>
#include<string.h>
int main(){
    int n;
    scanf("%d", &n);
    
    int dq[1000];
    int f = 0,r = -1;
    char cmd[30];
    scanf("%d", &n);
    while(n--) {
        scanf("%s", cmd);
            if(!strcmp(cmd, "priority_board")==0) {
                        scanf("%d", &x);
            if ( f == -1) {
                f = r = 0;
                }else {
                    f--;
                }
                for (int i = r; i >= f; --i)
                dq[i + 1] = dq[i];
                r++;
            } else {
                f--;
            }
            dq[f] = x;
            if (r < f) r = f;
        }
        else if (!strcmp(cmd, "general_board")){
            int x; scanf("%d", &x);
            dq[++r] = x;
        }
        else if (!strcmp(cmd, "board train")){
            if(f > r) printf("Invalid operation\n");
            else f++;
        }
        else if (!strcmp(cmd, "display")) {
{
            if(f > r) { printf("No passengers\n");
           } else {
                for(int i = f;i <= r; i++)
                printf("%d ", dq[i]);
           }
                printf("\n");
            }
        }
    }
    return 0;
}