#include <iostream>

using namespace std;

char s[100005];

int n,m;

int judge(int l,int r)

{

    for(int i = l;i <= r;i ++)

    {

        if(s[i] != s[n-i+1])

        {

            return 0;

        }

    }

    return 1;

}

int main(int argc, char *argv[]) {

    scanf("%d%d",&n,&m);

    scanf("%s",s+1);

    for(int i = 0;i < m;++ i)

    {

        int x,y;

        char c;

        scanf("%d %d %c",&x,&y,&c);

        if(x == 1)

        {

            s[y] = c;

            continue;

        }

        if(x == 2)

        {

            if(judge(y,c-'0')){

                printf("YES\n");

            }

            else printf("NO\n");

        }

    }

}