#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;
const int maxn = 300000;
int n,q;
int a[maxn+1];
int f[maxn+1];
struct Node
{
int value;
int l,r;
int leftNode,rightNode;
};
vector<Node> V;
int initIT(int x,int y)
{
Node res;
res.l = x;
res.r = y;
if (x==y)
res.value = a[x];
else
{
int m=(x+y)/2;
int p1=initIT(x,m);
int p2=initIT(m+1,y);
res.leftNode = p1;
res.rightNode = p2;
res.value = V[p1].value+V[p2].value;
}
V.push_back(res);
return V.size()-1;
}
int updateIT(int oldRoot,int x,int v)
{
Node res;
res.l = V[oldRoot].l;
res.r = V[oldRoot].r;
if (V[oldRoot].l==V[oldRoot].r)
{
res.value = v;
V.push_back(res);
return V.size()-1;
}
else
{
int leftNode = V[oldRoot].leftNode;
int rightNode = V[oldRoot].rightNode;
if (x<=V[leftNode].r)
{
res.leftNode = updateIT(leftNode,x,v);
res.rightNode = rightNode;
res.value = V[res.leftNode].value + V[res.rightNode].value;
}
else
{
res.leftNode = leftNode;
res.rightNode = updateIT(rightNode,x,v);
res.value = V[res.leftNode].value + V[res.rightNode].value;
}
V.push_back(res);
return V.size()-1;
}
}
int getIT(int i,int x,int y)
{
int res = 0;
if (y<V[i].l or x>V[i].r) res = 0;
else
if (x<=V[i].l and V[i].r<=y) res = V[i].value;
else
{
int res1 = getIT(V[i].leftNode,x,y);
int res2 = getIT(V[i].rightNode,x,y);
res=res1+res2;
}
return res;
}
int root[maxn+1];
int main()
{
ios_base::sync_with_stdio(0);
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
cin >> n >> q;
for (int i=1; i<=n; i++)
{
char c;
cin >> c;
a[i]=c-'0';
}
root[0] = initIT(1,n);
//cout << getIT(root[0],1,5) << '\n';
for (int i=1; i<=q; i++)
{
string op;
cin >> op;
root[i] = root[i-1];
if (op[0]=='t')
{
int j;
cin >> j;
root[i] = updateIT(root[i-1],j,1);
}
else
{
int a,b;
cin >> a >> b;
b--;
int dau=0,cuoi=i-1;
do
{
int giua=(dau+cuoi)/2;
if (getIT(root[giua],a,b)==b-a+1)
cuoi=giua-1;
else
dau=giua+1;
}
while (dau<=cuoi);
cout << i-dau << '\n';
}
}
return 0;
}
