#include<bits/stdc++.h>
#define ll unsigned long long
#define mod 1000000007
#define fast ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
using namespace std;

const ll m = 1e9+9;
const ll p = 131;
ll hashString(string s) {
    ll ans = 0;
    ll p_pow = 1;
    for(ll i=0; i<s.size(); i++) {
        ans = (ans + (s[i]-'a'+1)*p_pow)%m;
        p_pow = (p_pow*p)%m;
    }
    return ans;
}

ll modpow(ll x, ll y) {
    ll res = 1;

    x = x % m;
    if (x == 0) return 0;
    while (y > 0)
    {
        if (y & 1)
            res = (res*x) % m;

        y = y>>1;
        x = (x*x) % m;
    }
    return res;
}

ll combine1(ll s1, ll s2, ll l1, ll l2) {
    // cout<<l1<<" "<<l2<<"::\n";
    ll val = modpow(p, l1);
    return ((s2*val)%mod+s1)%mod;
}

ll combine2(ll s1, ll s2, ll l1, ll l2) {
    ll val = modpow(p, l2);
    return ((s1*val)%mod+s2)%mod;
}


struct segmentTree {
    vector<ll> t1, t2;
    string s;
    ll n;

    segmentTree(ll n) {
        this->n = n;
        t1.resize(4*n);
        t2.resize(4*n);
    }

    segmentTree(string s) : segmentTree(s.size()) {
        this->s = s;
        build(1, 0, n-1);
    }

    void build(ll v, ll tl, ll tr) {
        if(tl==tr) {
            t1[v] = s[tl]-'a'+1;
            t2[v] = t1[v];
        }
        else {
            ll tm = (tl+tr)/2;
            build(v*2, tl, tm);
            build(v*2+1, tm+1, tr);
            if(tm-tl+1==0) {
                t1[v] = t1[v*2+1];
                t2[v] = t2[v*2+1];
            }
            else if(tr-tm==0) {
                t1[v] = t1[v*2];
                t2[v] = t2[v*2];
            }
            else {
                t1[v] = combine1(t1[v*2], t1[v*2+1], tm-tl+1, tr-tm);
                t2[v] = combine2(t2[v*2], t2[v*2+1], tm-tl+1, tr-tm);
            }
        }
        // cout<<tl<<" "<<tr<<" "<<t1[v]<<" "<<t2[v]<<" "<<"::\n";
    }

    void update(ll v, ll tl, ll tr, ll pos, char new_val) {
        if(tl==tr) {
            // cout<<new_val<<"::\n";
            t1[v] = (new_val-'a'+1);
            t2[v] = t1[v];
        }
        else {
            ll tm = (tl+tr)/2;
            if(pos<=tm)
                update(v*2, tl, tm, pos, new_val);
            else
                update(v*2+1, tm+1, tr, pos, new_val);
            if(tm-tl+1==0) {
                t1[v] = t1[v*2+1];
                t2[v] = t2[v*2+1];
            }
            else if(tr-tm==0) {
                t1[v] = t1[v*2];
                t2[v] = t2[v*2];
            }
            else {
                t1[v] = combine1(t1[v*2], t1[v*2+1], tm-tl+1, tr-tm);
                t2[v] = combine2(t2[v*2], t2[v*2+1], tm-tl+1, tr-tm);
            }

        }
    }

    vector<ll> sum(ll v, ll tl, ll tr, ll l, ll r) {
        if(l>r)
            return {0, 0, 0};
        if(l==tl && r==tr)
            return {t1[v], t2[v], r-l+1};
        ll tm = (tl+tr)/2;
        vector<ll> a = sum(v*2, tl, tm, l, min(r, tm));
        vector<ll> b = sum(v*2+1, tm+1, tr, max(l, tm+1), r);

        if(a[2]==0)return {
                    b[0],
                    b[1],
                    a[2]+b[2]
                };
        else if(b[2]==0)return {
                    a[0],
                    a[1],
                    a[2]+b[2]
                };
        else
            return {
                    combine1(a[0], b[0], a[2], b[2]),
                    combine2(a[1], b[1], a[2], b[2]),
                    a[2]+b[2]
                };
    }
};

int main() {
    #ifndef ONLINE_JUDGE
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    #endif

    // fast;
    ll t = 1;
    // cin>>t;
    while(t--) {
        ll n, m;
        cin>>n>>m;
        string s;   cin>>s;

        segmentTree tree(s);
        // cout<<"end::\n";
        // assert(s.size()==tree.sum(1, 0, n-1, 0, n-1)[2]);
        // cout<<hashString(s)<<" "<<tree.sum(1, 0, n-1, 0, n-1)[0]<<"::\n";
        // cout<<(hashString(s)==tree.sum(1, 0, n-1, 0, n-1)[0])<<"::\n";
        ll q, k, a, b;
        char x;
        for(ll i=0; i<m; i++) {
            cin>>q;
            if(q==1) {
                cin>>k>>x;
                // cout<<x<<"::\n";
                tree.update(1, 0, n-1, k-1, x);
            }
            else {
                cin>>a>>b;
                vector<ll> value = tree.sum(1, 0, n-1, a-1, b-1);
                assert(value[2]==b-a+1);
                if(value[0]==value[1]) {
                    cout<<"YES\n";
                }
                else {
                    cout<<"NO\n";
                }
            }
        }
    }

}