#include <iostream>
#include <vector>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <string>
#include <queue>
#include <stack>
#include <bitset>
using namespace std;
#define pb(x) push_back(x)
#define ll long long
#define mk(x, y) make_pair(x, y)
#define lson l, m, rt<<1
#define mem(a) memset(a, 0, sizeof(a))
#define rson m+1, r, rt<<1|1
#define mem1(a) memset(a, -1, sizeof(a))
#define mem2(a) memset(a, 0x3f, sizeof(a))
#define rep(i, n, a) for(int i = a; i<n; i++)
#define fi first
#define se second
typedef pair<int, int> pll;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int mod = 1e9+7;
const int inf = 1061109567;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
const int maxn = 2e6+5;
int head[2005], num, n, m, top, cnt, deep;
int instack[2005], st[2005], low[2005], dfn[2005], id[2005];
struct node
{int to, nextt;
}e[maxn*2];
void add(int u, int v) {e[num].to = v, e[num].nextt = head[u], head[u] = num++;
}
void tarjan(int u) {instack[u] = 1;st[++top] = u;dfn[u] = low[u] = ++deep;for(int i = head[u]; ~i; i = e[i].nextt) {int v = e[i].to;if(!dfn[v]) {tarjan(v);low[u] = min(low[u], low[v]);} else if(instack[v]) {low[u] = min(low[u], dfn[v]);}}int v;if(dfn[u] == low[u]) {++ cnt;do {v = st[top--];instack[v] = 0;id[v] = cnt;} while(v != u);}
}
void solve() {for(int i = 0; i < n; i++) {if(!dfn[i])tarjan(i);}int flag = 0;for(int i = 0; i<n; i++) {if(id[i] == id[i+n]) {flag = 1;}}if(flag) {puts("NO");} else {puts("YES");}
}
void read() {char s[5];int u, v, w;for(int i = 0; i<m; i++) {scanf("%d%d%d", &u, &v, &w);scanf("%s", s);if(w) {if(s[0] == 'A') {add(u, u + n);add(v, v + n);} else if(s[0] == 'O') {add(u, v + n);add(v, u + n);} else {add(u, v + n);add(v, u + n);}} else {if(s[0] == 'A') {add(u + n, v);add(v + n, u);} else if(s[0] == 'O') {add(u + n, u);add(v + n, v);} else {add(u, v);add(v, u);add(v + n, u + n);add(u + n, v + n);}}}
}
void init() {num = top = cnt = deep = 0;mem1(head);mem(instack);mem(dfn);mem(low);
}
int main()
{cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);while(cin>>n>>m) {init();read();solve();}return 0;
}