#include <bits/stdc++.h>
using namespace std;
const int N = 1e5;
const int OFF = 1 << 18;
struct Node {
int pref = 0, suf = 0;
int maks = 0, sum = 0;
void set(int value) {
pref = max(pref, value);
suf = max(suf, value);
maks = max(maks, value);
sum = value;
}
} tour[OFF][2], e;
Node merge(const Node& L, const Node& R) {
Node ret;
ret.pref = max(L.pref, L.sum + R.pref);
ret.suf = max(R.suf, L.suf + R.sum);
ret.maks = max(L.maks, R.maks);
ret.maks = max(ret.maks, L.suf + R.pref);
ret.sum = L.sum + R.sum;
return ret;
}
int value(char c, bool flag) {
if ((c == 'P') ^ flag) return 1;
return -1;
}
int n, q;
string s;
void con(int x, int l, int r, bool flag) {
if (l == r) {
tour[x][flag].set(value(s[l], flag));
} else {
int mid = (l + r) >> 1;
con(x * 2 + 1, l, mid, flag);
con(x * 2 + 2, mid + 1, r, flag);
tour[x][flag] = merge(tour[x * 2 + 1][flag], tour[x * 2 + 2][flag]);
}
}
Node get(int x, int l, int r, int ql, int qr, bool flag) {
if (ql <= l && r <= qr) return tour[x][flag];
if (ql > r || l > qr) return e;
int mid = (l + r) >> 1;
return merge(
get(x * 2 + 1, l, mid, ql, qr, flag),
get(x * 2 + 2, mid + 1, r, ql, qr, flag)
);
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n >> q;
cin >> s;
con(0, 0, n - 1, 0);
con(0, 0, n - 1, 1);
while (q--) {
int l, r;
cin >> l >> r, --l, --r;
Node X = get(0, 0, n - 1, l, r, 0);
Node Y = get(0, 0, n - 1, l, r, 1);
cout << max(X.maks, Y.maks) << "\n";
}
return 0;
}
