#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;
const int N = 1e5 + 5;
vector<int> ed[N];
int n, q, cnt;
int a[N], Lc, Rc;
int dfn[N], rnk[N], top[N], siz[N], son[N], fa[N], h[N];
struct segt {
    int d[N * 4], lc[N * 4], rc[N * 4], tg[N * 4];
    void pushup(int p) {
        d[p] = d[p << 1] + d[(p << 1) | 1];
        lc[p] = lc[p << 1];
        rc[p] = rc[(p << 1) | 1];
        if(rc[p << 1] == lc[(p << 1) | 1])
            --d[p];
    }
    void _fill(int p, int x) {
        d[p] = 1;
        tg[p] = lc[p] = rc[p] = x;
    }
    void pushdown(int p) {
        if(!tg[p]) return;
        _fill(p << 1, tg[p]);
        _fill((p << 1) | 1, tg[p]);
        tg[p] = 0;
    }
    void build(int l, int r, int p) {
        if(l == r) {
            d[p] = 1;
            lc[p] = rc[p] = a[rnk[l]];
            tg[p] = 0;
            return;
        }
        int mid = (l + r) >> 1;
        build(l, mid, p << 1);
        build(mid + 1, r, (p << 1) | 1);
        pushup(p);
    }
    void modify(int l, int r, int s, int t, int o, int p) {
        if(s <= l && r <= t) {
            _fill(p, o);
            return;
        }
        pushdown(p);
        int mid = (l + r) >> 1;
        if(s <= mid) modify(l, mid, s, t, o, p << 1);
        if(t > mid) modify(mid + 1, r, s, t, o, (p << 1) | 1);
        pushup(p);
    }
    int query(int l, int r, int s, int t, int p) {
        if(s <= l && r <= t) {
            if(r == t) Rc = rc[p];
            if(l == s) Lc = lc[p];
            return d[p];
        }
        pushdown(p);
        int mid = (l + r) >> 1;
        if(t <= mid) return query(l, mid, s, t, p << 1);
        if(s > mid) return query(mid + 1, r, s, t, (p << 1) | 1);
        int ret = query(l, mid, s, t, p << 1) + query(mid + 1, r, s, t, (p << 1) | 1);
        if(rc[p << 1] == lc[(p << 1) | 1])
            --ret;
        return ret;
    }
} tr;
void dfs1(int x) {
    siz[x] = 1;
    son[x] = -1;
    for(auto p : ed[x])
        if(!h[p]) {
            h[p] = h[x] + 1;
            fa[p] = x;
            dfs1(p);
            siz[x] += siz[p];
            if(son[x] == -1 || siz[son[x]] < siz[p])
                son[x] = p;
        }
}
void dfs2(int x, int tp) {
    top[x] = tp;
    rnk[dfn[x] = ++cnt] = x;
    if(~son[x]) {
        dfs2(son[x], tp);
        for(auto p : ed[x])
            if(p != son[x] && p != fa[x])
                dfs2(p, p);
    }
}
void modify_path(int x, int y, int o) {
    while(top[x] != top[y]) {
        if(h[top[x]] < h[top[y]]) swap(x, y);
        tr.modify(1, n, dfn[top[x]], dfn[x], o, 1);
        x = fa[top[x]];
    }
    if(h[x] > h[y]) swap(x, y);
    tr.modify(1, n, dfn[x], dfn[y], o, 1);
}
int query_path(int x, int y) {
    int la = 0, lb = 0, ans = 0;
    while(top[x] != top[y]) {
        if(h[top[x] < h[top[y]]]) {
            swap(x, y);
            swap(la, lb);
        }
        ans += tr.query(1, n, dfn[top[x]], dfn[x], 1);
        if(Rc == la) --ans;
        la = Lc;
        x = fa[top[x]];
    }
    if(h[x] > h[y]) {
        swap(x, y);
        swap(la, lb);
    }
    ans += tr.query(1, n, dfn[x], dfn[y], 1);
    if(Rc == lb) --ans;
    if(Lc == la) --ans;
    return ans;
}
char c[10];
int u, v, w;
int main() {
    scanf("%d%d", &n, &q);
    for(int i = 1; i <= n; ++i)
        scanf("%d", &a[i]);
    for(int i = 1; i < n; ++i) {
        scanf("%d%d", &u, &v);
        ed[u].push_back(v);
        ed[v].push_back(u);
    }
    h[1] = 1;
    dfs1(1);
    dfs2(1, 1);
    tr.build(1, n, 1);
    while(q--) {
        scanf("%s%d%d", c, &u, &v);
        if(c[0] == 'C') {
            scanf("%d", &w);
            modify_path(u, v, w);
        } else
            printf("%d\n", query_path(u, v));
    }
}

WA.record