#include <cstdio>#include <cstring>#include <algorithm>#include <climits>#include <string>#include <iostream>#include <map>#include <cstdlib>#include <list>#include <set>#include <queue>#include <stack>using namespace std;#define lson l,mid,rt<<1#define rson mid+1,r,rt<<1|1int sum[888888];void up(int rt){    sum[rt] = max(sum[rt << 1], sum[rt << 1 | 1]);}void build(int l, int r, int rt){    if (l == r){        scanf("%d", &sum[rt]); return;    }    int mid = (l + r) >> 1;    build(lson);    build(rson);    up(rt);}int ask(int L, int R, int l, int r, int rt){    if (L <= l&&r <= R)return sum[rt];    int mid = (l + r) >> 1;    int ans = 0;    if (L <= mid) ans = max(ans, ask(L, R, lson));    if (R>mid) ans = max(ans, ask(L, R, rson));    return ans;}void update(int key, int add, int l, int r, int rt){    if (l == r){        sum[rt] = add; return;    }    int mid = (l + r) >> 1;    if (key <= mid) update(key, add, lson);    else update(key, add, rson);    up(rt);}int main(){    int n, m;    int a, b;    char str[100];    while (scanf("%d%d", &n, &m) != EOF){        build(1, n, 1);        for (int i = 0; i<m; i++){            scanf("%s", str);            scanf("%d%d", &a, &b);            if (str[0] == ‘U‘){                update(a, b, 1, n, 1);            }            else printf("%d\n", ask(a, b, 1, n, 1));        }    }    return 0;}