#include <bits/stdc++.h>
using namespace std;
const int mxN = (int)3e5+10;
string s;
int n, q, segTree[2*mxN];
void upd(int x, int v, int p=0, int l=1, int r=n){
if(l==r){ segTree[p]=v; return; }
int mid = (l+r)>>1; int rp = p+2*(mid-l+1);
if(x<=mid) upd(x,v,p+1,l,mid);
else upd(x,v,rp,mid+1,r);
segTree[p] = max(segTree[p+1],segTree[rp]);
}
int query(int i, int j, int p=0, int l=1, int r=n){
if(i>r or j<l or i>j) return 0;
if(i<=l and r<=j) return segTree[p];
int mid = (l+r)>>1; int rp = p+2*(mid-l+1);
return max(query(i,j,p+1,l,mid),query(i,j,rp,mid+1,r));
}
int32_t main() {
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n >> q >> s;
fill(segTree,segTree+mxN*2,mxN);
for(int i = 0; i < n; i++) upd(i+1,(s[i]=='1')?0:mxN);
for(int i = 1; i <= q; i++){
int x, y; cin >> s >> x;
if(s[0]=='t') upd(x,i);
else cin >> y, y--, cout << (query(x,y)!=mxN)*(i-query(x,y)) << "\n";
}
}
