#include <bits/stdc++.h>
#define all(x) x.begin(),x.end()
#define sz(x) ((int)x.size())
#define pll pair<ll, ll>
#define MP make_pair
#define PB push_back
#define pii pair<int, int>
#define pi3 pair<pii, int>
#define ft first
#define sd second
#define MP3(a,b,c) MP(MP(a,b),c)
using namespace std;
typedef long long ll;
const int N = 300100;
const int Q = 300100;
const int oo = 2e9;
const int B = 1;
string s, qr;
int n, q, mn[N], l[N], r[N], st[4 * N];
bool typ[N];
void build(int v, int l, int r){
if (l == r) {
st[v] = mn[l];
return;
}
int md = (l + r) >> 1;
build(v + v, l, md);
build(v + v + 1, md + 1, r);
st[v] = max(st[v + v], st[v + v + 1]);
}
int get(int v, int tl, int tr, int l, int r){
if (l > r) return -q;
if (tl == l && tr == r) return st[v];
int md = (tl + tr) >> 1;
return max(get(v + v, tl, md, l, min(r, md)),
get(v + v + 1, md + 1, tr, max(md + 1, l), r));
}
int main(){
#ifdef _LOCAL
freopen("in.txt","r",stdin);
#else
ios_base::sync_with_stdio(0); cin.tie(0);
#endif // _LOCAL
cin >> n >> q >> s;
for (int i = 0; i < n; i++){
mn[i] = (s[i] == '1' ? -1 : q);
}
for (int i = 0; i < q; i++){
string qr; cin >> qr;
if (qr[0] == 't'){
typ[i] = 1;
int x; cin >> x;
x--;
mn[x] = i;
} else {
cin >> l[i] >> r[i];
l[i]--;
r[i] -= 2;
}
}
build(1, 0, n - 1);
for (int i = 0; i < q; i++)
if (!typ[i])
cout << max(0, i - get(1, 0, n - 1, l[i], r[i])) << '\n';
return 0;
}
