#include <bits/stdc++.h>

using namespace std;

const int BUFFER_SIZE = 1 << 20;
char rb[BUFFER_SIZE], *rp = rb, *rt = rb;
inline char read_char() {
    return rp == rt ? (rt = rb + fread(rb, 1, BUFFER_SIZE, stdin), rp = rb, *rp ++) : *rp ++;
}
inline int read_int() {
    int x = 0;
    char ch = read_char(), flag = 0;
    while (ch != '-' && (ch < '0' || ch > '9')) {
        ch = read_char();
    }
    if (ch == '-') {
        flag = 1;
        ch = read_char();
    }
    for (x = 0; ch >= '0' && ch <= '9'; ch = read_char()) {
        x = x * 10 + (ch - '0');
    }
    return flag ? -x : x;
}

char wb[BUFFER_SIZE], *wp = wb;
inline void write_flush() {
    fwrite(wb, 1, wp - wb, stdout);
    wp = wb;
}
inline void write_char(char c) {
    *wp ++ = c;
    if (wp == wb + BUFFER_SIZE) {
        write_flush();
    }
}
inline void write_int(int x) {
    if (x == 0) {
        write_char('0');
    } else if (x < 0) {
        write_char('-');
        x = -x;
    }
    static char b[32], i;
    for (i = 1; x; i ++) {
        b[i] = x % 10 + '0';
        x /= 10;
    }
    for (i --; i; i --) {
        write_char(b[i]);
    }
}

using namespace std;

const int MAX_N = 1000000 + 5;
const int P = 1000000007;

int N, Q;
int a[MAX_N], f[MAX_N], g[MAX_N][3];
int elast[MAX_N], ey[MAX_N << 1], enext[MAX_N << 1];

void dfs(int u, int fa) {
    f[u] = fa;
    for (int j = elast[u], v; j; j = enext[j]) {
        if ((v = ey[j]) != fa) {
            dfs(v, u);
        }
    }
}

int main() {
    N = read_int(), Q = read_int();
    for (int i = 1; i <= N; i ++) {
        a[i] = read_int();
    }
    for (int i = 1, j = 1; i < N; i ++) {
        int x = read_int(), y = read_int();
        ey[j] = y, enext[j] = elast[x], elast[x] = j ++;
        ey[j] = x, enext[j] = elast[y], elast[y] = j ++;
    }
    dfs(1, 0);
    for (int i = 1; i <= N; i ++) {
        for (int j = 0, y = i; j <= 2 && y; j ++, y = f[y]) {
            g[y][j] ^= a[i];
        }
    }
    int ans = 0;
    for (int i = 1, ii = 0; i <= Q; i ++) {
        int x = read_int(), b = read_int();
        for (int j = 0, y = x; j <= 2 && y; j ++, y = f[y]) {
            g[y][j] ^= a[x] ^ b;
        }
        a[x] = b;
        int res = g[x][2] ^ g[x][1];
        x = f[x], res ^= g[x][1] ^ g[x][0];
        x = f[x], res ^= g[x][0];
        ii += i * 2 - 1;
        ii -= ii >= P ? P : 0;
        ans = (ans + 1ll * res * ii) % P;
    }
    write_int(ans), write_char('\n');
    write_flush();
    return 0;
}