#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T>
ostream_iterator<T> oit(const string &s = " "){ return ostream_iterator<T>(cout,s.c_str()); }
inline auto rep(int l, int r) { return views::iota(min(l, r), r); }
inline auto rep(int n) { return rep(0, n); }
inline auto rep1(int l, int r) { return rep(l, r + 1); }
inline auto rep1(int n) { return rep(1, n + 1); }
inline auto per(int l, int r) { return rep(l, r) | views::reverse; }
inline auto per(int n) { return per(0, n); }
inline auto per1(int l, int r) { return per(l, r + 1); }
inline auto per1(int n) { return per(1, n + 1); }
#define A(a) begin(a),end(a)
inline auto len = ranges::ssize;

struct chash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
template<typename T, typename U> using pb_map = gp_hash_table<T, U, chash>;
template<typename T> using pb_set = gp_hash_table<T, null_type, chash>;
#define K first
#define V second

using ll = long long;
using ld = long double;

using vi = vector<int>;
using vii = vector<vector<int>>;
typedef vector<ll> vll;
using pll = pair<ll,ll>;
using pii = pair<int,int>;

constexpr ll NN = 2e5, M = 1000000007, L = 20;

ll f1[NN], f2[NN];
ll inv(ll a, ll b=M) { return 1 < a ? b - inv(b % a, a) * b / a : 1; } // inv a mod b
ll choose(ll n, ll k) { return f1[n] * f2[k] % M * f2[n - k] % M; } // n choose k

void run()
{
    int s, n;
    cin>>s>>n;
    vi yes, no;
    for (int i = 0; i < n; i++) {
        int d;
        char t;
        cin>>d>>t;

        if (t == 'y') {
            yes.push_back(d);
        } else {
            no.push_back(d);
        }
    }
    sort(A(yes));
    sort(A(no));
    reverse(A(yes));

    set<int> taken;
    for (auto x : yes) {
        int t = x;
        if (taken.size()) t = min(t, *taken.begin() - 1);
        taken.insert(t);
    }
    if (taken.size() && *taken.begin() <= 0) {
        cout << "No";
        return;
    }

    int idx = 0;
    int t = 0;
    while (idx < (int)no.size()) {
        t++;
        if (t > no[idx]) {
            cout << "No";
            return;
        }
        if (taken.count(t)) idx += s - 1;
        else idx += s;
    }
    cout << "Yes";
}

int main()
{
    //KING OF THE WORLD...... U.W.T.B
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    run();
}