#include <bits/stdc++.h>

using namespace std;

#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

#define ll long long
#define ld long double
#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define FOR(i,l,r) for(int i=(l);i<=(r);i++)
#define ROF(i,r,l) for(int i=(r);i>=(l);i--)
int inf=1000000007;
ll infl=1000000000000000007;
ll mod=1000000007;
ll mod1=998244353;

const int N=300007,pot=1<<19;

int seg[2*pot+7];

void ins(int v,int x)
{
	v+=pot-1;
	seg[v]=x;
	while(v>1)
	{
		v/=2;
		seg[v]=max(seg[2*v],seg[2*v+1]);
	}
}
int que(int v,int a,int b,int l,int r)
{
	if(a<=l&&b>=r) return seg[v];
	if(r<a||l>b) return 0;
	return max(que(2*v,a,b,l,(l+r)/2),que(2*v+1,a,b,(l+r)/2+1,r));
}

bool is[N];

signed main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n,q;
	cin>>n>>q;
	string s;
	cin>>s;
	FOR(i,1,n) 
	{
		is[i]=s[i-1]-'0';
		if(is[i]) ins(i,0);
		else ins(i,inf);
	}
	FOR(i,1,q)
	{
		string s;
		cin>>s;
		if(s[0]=='t')
		{
			int x;
			cin>>x;
			ins(x,i);
		}
		else 
		{
			int a,b;
			cin>>a>>b;
			int t=que(1,a,b-1,1,pot);
			cout<<max(0,i-t)<<endl;
		}
	}
	
	return 0;
}