#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, U b) {
  if (a < b) a = b;
}
template <typename T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T, class T1>
inline void gn(T &first, T1 &second) {
  gn(first);
  gn(second);
}
template <class T, class T1, class T2>
inline void gn(T &first, T1 &second, T2 &z) {
  gn(first);
  gn(second);
  gn(z);
}
template <typename T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <typename T>
inline void println(T first) {
  print(first), putchar('\n');
}
template <typename T>
inline void printsp(T first) {
  print(first), putchar(' ');
}
template <class T, class T1>
inline void print(T first, T1 second) {
  printsp(first), println(second);
}
template <class T, class T1, class T2>
inline void print(T first, T1 second, T2 z) {
  printsp(first), printsp(second), println(z);
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = 1LL * a * a % m)
    if (b & 1) ans = 1LL * ans * a % m;
  return ans;
}
vector<int> ans;
int mn[1000100], mx[1000100];
int arr[1000100], nn;
int mid[1000100], mxx[1000100], nxt[1000100];
int B[1000100];
void update(int u, int val) {
  while (u < 1000100) {
    smax(B[u], val);
    u += u & -u;
  }
}
int calc(int u) {
  int ans = 0;
  while (u) {
    smax(ans, B[u]);
    u -= u & -u;
  }
  return ans;
}
void gameover() {
  puts("IMPOSSIBLE");
  exit(0);
}
void solve(int L, int R) {
  if (L > R) return;
  if (mn[L] >= mx[L]) gameover();
  if (L == R) {
    ans.push_back(L);
    return;
  }
  int nxt = arr[lower_bound(arr, arr + nn, L) - arr];
  if (nxt > L) {
    for (int i = min(R, nxt - 1); i >= L; i--) ans.push_back(i);
    solve(nxt, R);
    return;
  }
  if (mid[L] >= mx[L]) gameover();
  solve(L + 1, mid[L]);
  ans.push_back(L);
  solve(mid[L] + 1, R);
}
int main() {
  int n, m;
  gn(n, m);
  int u, v;
  char s[11];
  arr[nn++] = n + 1;
  for (int i = 1; i <= n; i++) mn[i] = i, mx[i] = n + 1;
  for (int i = 0; i < m; i++) {
    gn(u, v);
    scanf("%s", s);
    if (u >= v) gameover();
    if (s[0] == 'L')
      smax(mn[u], v);
    else
      smin(mx[u], v);
    arr[nn++] = u;
    smax(mxx[u], v);
  }
  sort(arr, arr + nn);
  nn = unique(arr, arr + nn) - arr;
  for (int i = n; i; i--) {
    mid[i] = max(i, calc(mn[i]));
    if (!mxx[i])
      nxt[i] = i;
    else
      nxt[i] = calc(mxx[i]);
    update(i, nxt[i]);
  }
  solve(1, n);
  for (int i = 0; i < ans.size(); i++) printsp(ans[i]);
  puts("");
  return 0;
}
