#include <iostream>#include <cstring>#include <cstdio>using namespace std;const int N = 100005;int a[N];struct Edge {    int to, next;} edge[N*2];int head[N], cntE;void addedge(int u, int v) {    edge[cntE].to = v; edge[cntE].next = head[u]; head[u] = cntE++;    edge[cntE].to = u; edge[cntE].next = head[v]; head[v] = cntE++;}int dep[N], fa[N], sz[N], son[N];void dfs1(int u, int pre, int d) {    dep[u] = d;    sz[u] = 1;    fa[u] = pre;    for (int i = head[u]; ~i; i = edge[i].next) {        int v = edge[i].to;        if (v != pre) {            dfs1(v, u, d+1);            sz[u] += sz[v];            if (son[u] == -1 || sz[v] > sz[son[u]]) son[u] = v;        }    }}int top[N], dfn[N], rk[N], idx;void dfs2(int u, int tp) {    top[u] = tp;    dfn[u] = ++idx;    rk[idx] = u;    if (son[u] == -1) return ;    dfs2(son[u], tp);    for (int i = head[u]; ~i; i = edge[i].next) {        int v = edge[i].to;        if (v != fa[u] && v != son[u]) {            dfs2(v, v);        }    }}int tr[N<<2], ltr[N<<2], rtr[N<<2]; // tr[i] means the number of color segmentint fg[N<<2];#define lson o<<1#define rson o<<1|1void pushup(int o) {    ltr[o] = ltr[lson];    rtr[o] = rtr[rson];    tr[o] = tr[lson] + tr[rson];    if (rtr[lson] == ltr[rson]) tr[o]--;}void pushdown(int o) {    if (fg[o]) {        tr[lson] = tr[rson] = 1;        fg[lson] = fg[rson] = fg[o];        ltr[lson] = ltr[rson] = ltr[o];        rtr[lson] = rtr[rson] = rtr[o];        fg[o] = 0;    }}void build(int o, int l, int r) {    fg[o] = 0;    if (l == r) {        tr[o] = 1;        ltr[o] = rtr[o] = a[rk[l]];        return;    }    int mid = (l+r) >> 1;    build(lson, l, mid);    build(rson, mid+1, r);    pushup(o);}void change(int o, int l, int r, int L, int R, int v) {    if (l >= L && r <= R) {        fg[o] = 1;        tr[o] = 1;        ltr[o] = rtr[o] = v;        return ;    }    pushdown(o);    int mid = (l+r) >> 1;    if (mid >= L) change(lson, l, mid, L, R, v);    if (mid < R) change(rson, mid+1, r, L, R, v);    pushup(o);}void CHANGE(int x, int y, int n, int c) {    while (top[x] != top[y]) {        if (dep[top[x]] < dep[top[y]]) swap(x, y);        change(1, 1, n, dfn[top[x]], dfn[x], c);        x = fa[top[x]];    }    if (dep[x] > dep[y]) swap(x, y);    change(1, 1, n, dfn[x], dfn[y], c);}int query(int o, int l, int r, int L, int R) {    if (l >= L && r <= R) return tr[o];    pushdown(o);    int mid = (l+r) >> 1;    if (mid < L) {        return query(rson, mid+1, r, L, R);    } else if (mid >= R) {        return query(lson, l, mid, L, R);    } else {        int ans = query(lson, l, mid, L, R);        ans += query(rson, mid+1, r, L, R);        if (ltr[rson] == rtr[lson]) ans--;        return ans;    }}int qq(int o, int l, int r, int p) {    if (l == r) return ltr[o];    pushdown(o);    int mid = (l+r) >> 1;    if (mid >= p) return qq(lson, l, mid, p);    return qq(rson, mid+1, r, p);}int QUERY(int x, int y, int n) {    int ans = 0;    while (top[x] != top[y]) {        if (dep[top[x]] < dep[top[y]]) swap(x, y);        ans += query(1, 1, n, dfn[top[x]], dfn[x]);        if (qq(1, 1, n, dfn[top[x]]) == qq(1, 1, n, dfn[fa[top[x]]])) --ans;        x = fa[top[x]];    }    if (dep[x] > dep[y]) swap(x, y);    ans += query(1, 1, n, dfn[x], dfn[y]);    return ans;}void init() {    memset(head, -1, sizeof head);    memset(son, -1, sizeof son);    idx = cntE = 0;}int main(){    //freopen("in.txt", "r", stdin);    int n, m;    while (~scanf("%d%d", &n, &m)) {        init();        for (int i = 1; i <= n; ++i) scanf("%d", &a[i]);        int u, v, c;        for (int i = 1; i < n; ++i) {            scanf("%d%d", &u, &v);            addedge(u, v);        }        dfs1(1, 0, 0); dfs2(1, 1); build(1, 1, n);        char op[10];        while (m--) {            scanf("%s", op);            if (*op == ‘Q‘) {                scanf("%d%d", &u, &v);                printf("%d\n", QUERY(u, v, n));            } else {                scanf("%d%d%d", &u, &v, &c);                CHANGE(u, v, n, c);            }        }    }    return 0;}