#include <iostream>

#include <sstream>

#include <algorithm>

#include <cstdio>

#include <math.h>

#include <set>

#include <map>

#include <queue>

#include <string>

#include <string.h>

#include <bitset>

#define REP(i,a,n) for(int i=a;i<=n;++i)

#define PER(i,a,n) for(int i=n;i>=a;--i)

#define hr putchar(10)

#define pb push_back

#define lc (o<<1)

#define rc (lc|1)

#define mid ((l+r)>>1)

#define ls lc,l,mid

#define rs rc,mid+1,r

#define x first

#define y second

#define io std::ios::sync_with_stdio(false)

#define endl '\n'

#define DB(a) ({REP(__i,1,n) cout<<a[__i]<<' ';hr;})

using namespace std;

typedef long long ll;

typedef pair<int,int> pii;

const int P = 1e9+7, P2 = 998244353, INF = 0x3f3f3f3f;

ll gcd(ll a,ll b) {return b?gcd(b,a%b):a;}

ll qpow(ll a,ll n) {ll r=1%P;for (a%=P;n;a=a*a%P,n>>=1)if(n&1)r=r*a%P;return r;}

ll inv(ll x){return x<=1?1:inv(P%x)*(P-P/x)%P;}

inline int rd() {int x=0;char p=getchar();while(p<'0'||p>'9')p=getchar();while(p>='0'&&p<='9')x=x*10+p-'0',p=getchar();return x;}

//head

const int N = 1e6+10;

int n, t;

char s[N];

struct _ {

	int v[2][2];

	void upd(int x) {

		if (x==1) v[0][0]=v[0][1]=v[1][0]=1,v[1][1]=0;

		else v[0][0]=0,v[0][1]=v[1][0]=v[1][1]=1;

	}

	_ operator + (const _ &rhs) const {

		_ ret;

		memset(ret.v,0x3f,sizeof ret.v);

		REP(k,0,1) REP(i,0,1) REP(j,0,1) {

			ret.v[i][j]=min(ret.v[i][j],v[i][k]+rhs.v[k][j]);

		}

		return ret;

	}

} tr[N<<2];

void pu(int o) {

	tr[o]=tr[lc]+tr[rc];

}

void build(int o, int l, int r) {

	l==r?tr[o].upd(s[l]-'0'):(build(ls),build(rs),pu(o));

}

void update(int o, int l, int r, int x, int v) {

	l==r?tr[o].upd(v):(mid>=x?update(ls,x,v):update(rs,x,v),pu(o));

}

_ qry(int o, int l, int r, int ql, int qr) {

	if (ql<=l&&r<=qr) return tr[o];

	if (mid>=qr) return qry(ls,ql,qr);

	if (mid<ql) return qry(rs,ql,qr);

	return qry(ls,ql,qr)+qry(rs,ql,qr);

}

int main() {

	scanf("%d%s", &n, s+1);

	build(1,1,n);

	scanf("%d", &t);

	while (t--) {

		int op, x, y;

		scanf("%d%d%d", &op, &x, &y);

		if (op==1) printf("%d\n",qry(1,1,n,x,y).v[0][0]);

		else update(1,1,n,x,y);

	}

}