#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define fst first
#define snd second
#define pb push_back
#define forn(i,a,b) for(int i = a; i<b; i++)
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define mset(a,v) memset(a,v,sizeof(a))
#define FIN ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
template <typename T>
using iset = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
#ifdef D
#define debug(x) cout<<x
#else
#define debug(x) //nothing
#endif
const int MAXN = 100000+5;
const int MAXP = 25;
string color;
ll n,q;
struct State{
ll aa=0;
ll rr=0;
ll ra = 0;
ll ar = 0;
State(ll aa=0, ll rr=0, ll ra = 0, ll ar = 0):aa(aa),rr(rr), ra(ra), ar(ar){}
};
State blift[MAXN][MAXP];
State merge(State a, State b){
State neww = State();
ll aux;
aux=min(a.ar,b.ar);
b.ar-=aux;
aux=min(a.aa,b.ar);
b.ar-=aux;
//
//////////////////////////////
aux=min(a.ra,b.ra);
b.ra-=aux;
aux=min(a.rr,b.ra);
b.ra-=aux;
//
//////////////////////////////
aux=min(a.rr,b.aa);
b.aa-=aux;
a.rr-=aux;
neww.ar+=aux;
aux=min(a.ra,b.aa);
a.ra-=aux;
b.aa-=aux;
neww.aa+=aux;
//////////////////////////////
aux=min(a.aa,b.rr);
a.aa-=aux;
b.rr-=aux;
neww.ra+=aux;
aux=min(a.ar,b.rr);
a.ar-=aux;
b.rr-=aux;
neww.rr+=aux;
neww.ar+=a.ar+b.ar;
neww.ra+=a.ra+b.ra;
neww.rr+=a.rr+b.rr;
neww.aa+=a.aa+b.aa;
return neww;
}
void precalc(){
forn(i,0,n) blift[i][0]=(color[i]=='P'?State(1,0,0,0):State(0,1,0,0));
forn(k,1,MAXP){
forn(i,0,n){
blift[i][k]=merge((i+(1<<(k-1))<n?blift[i+(1<<(k-1))][k-1]:State()), blift[i][k-1]);
debug(" State "<<i<<" "<<(1<<k)<<" aa= "<<blift[i][k].aa<<" rr= "<<blift[i][k].rr<<" ra= "<<blift[i][k].ra<<" ar= "<<blift[i][k].ar<<'\n');
}
}
}
int main(){ cin>>n>>q;
cin>>color;
precalc();
forn(i,0,q){
ll l,r; cin>>l>>r;
l--; r--;
State res = State();
for(int k = MAXP-1; k>=0; k--){
if(l+(1<<k)-1<=r){
debug("haciendo "<<l<<" "<<(1<<k)<<'\n');
res=merge(blift[l][k],res);
l+=(1<<k);
}
if(l-1==r) break;
}
cout<<res.ar+res.ra+res.rr+res.aa<<'\n';
}
return 0;
}
