#include <bits/stdc++.h>
using namespace std;
template <typename T>
T gcd(T x, T y) {
  while (y > 0) {
    x %= y;
    swap(x, y);
  }
  return x;
}
template <class _T>
inline _T sqr(const _T& x) {
  return x * x;
}
template <class _T>
inline string tostr(const _T& a) {
  ostringstream os("");
  os << a;
  return os.str();
}
const long double PI = 3.1415926535897932384626433832795L;
template <typename T>
inline void input(T& a) {
  static int c;
  a = 0;
  while (!isdigit(c = getchar()) && c != '-') {
  }
  char neg = 0;
  if (c == '-') {
    neg = 1;
    c = getchar();
  }
  while (isdigit(c)) {
    a = 10 * a + c - '0';
    c = getchar();
  }
  if (neg) a = -a;
}
template <typename T = int>
inline T nxt() {
  T res;
  input(res);
  return res;
}
void solve() {}
void imp() {
  puts("IMPOSSIBLE");
  exit(0);
}
const int N = 1000010;
vector<int> q[N][2];
int g[N][2];
int r[N];
int maleft[N];
int miright[N];
int n;
int dfs(int v, int le, int ri) {
  if (r[v] >= ri) {
    imp();
  }
  if (v >= ri) {
    imp();
  }
  if (le >= ri) {
    imp();
  }
  if (maleft[v] > v) {
    g[v][0] = v + 1;
    int ret = dfs(v + 1, maleft[v], min(ri, miright[v]));
    le = max(le, r[v]);
    if (ret < le) {
      g[v][1] = ret + 1;
      return dfs(ret + 1, le, ri);
    } else {
      return ret;
    }
  } else {
    le = max(le, r[v]);
    if (v < le) {
      g[v][1] = v + 1;
      return dfs(v + 1, le, ri);
    }
  }
  return v;
}
void print(int v) {
  if (v >= n) {
    return;
  }
  if (g[v][0]) {
    print(g[v][0]);
  }
  printf("%d ", v + 1);
  if (g[v][1]) {
    print(g[v][1]);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int c;
  n = nxt();
  c = nxt();
  char s[10];
  for (int i = 0; i < c; ++i) {
    int a = nxt() - 1;
    int b = nxt() - 1;
    if (b <= a) {
      imp();
    }
    scanf("%s", s);
    if (s[0] == 'L') {
      q[a][0].push_back(b);
    } else {
      q[a][1].push_back(b);
    }
  }
  for (int i = 0; i < n; ++i) {
    r[i] = i;
    maleft[i] = i;
    miright[i] = INT_MAX;
  }
  for (int i = n - 2; i >= 0; --i) {
    for (int x : q[i][0]) {
      r[i] = max(r[i], r[x]);
    }
    for (int x : q[i][1]) {
      r[i] = max(r[i], r[x]);
    }
    for (int x : q[i][0]) {
      maleft[i] = max(maleft[i], r[x]);
    }
    for (int x : q[i][1]) {
      miright[i] = min(miright[i], x);
    }
    if (miright[i] <= maleft[i]) {
      imp();
    }
  }
  int val = dfs(0, n - 1, n);
  assert(val == n - 1);
  print(0);
  puts("");
  return 0;
};
