#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long ll;
typedef vector<ll> vii;
typedef pair<ll,ll> pii;
typedef tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
#define F first
#define S second
#define pb push_back
#define all(v) v.begin(),v.end()
#define pow poww
const ll M=500000;
const ll mod=998244353;
const ll inf=2e18;
ll pow(ll x,ll y){
ll res=1;
while(y>0){
if((y&1))
res*=x,res%=mod;
x*=x,x%=mod;
y=(y>>1);
}
return res;
}
string s,t;
int n,q;
bool x=0;
void p(char &c,int x){
c+=x;
if(c>'z'||c<'a')
c-=26;
}
int main(){
ios_base::sync_with_stdio(0),cin.tie(0);
ll TC=1;
//cin>>TC;
while(TC--){
cin>>n>>q>>s>>t;
string ss=s;
for(int i=0;i<n-1;i++){
while(t[i]!='a')
p(t[i],1),p(t[i+1],1);
}
for(int i=0;i<n-1;i++){
p(ss[i+1],(26-(ss[i]-'a'))%26),p(ss[i],(26-(ss[i]-'a'))%26);
}
if(ss.back()==t.back())
cout<<"da\n";
else
cout<<"ne\n";
while(q--){
int ind;
char c;
cin>>ind>>c;
ind--;
s[ind]=c;
ss=s;
for(int i=0;i<n-1;i++){
p(ss[i+1],(26-ss[i]+'a')%26),p(ss[i],(26-ss[i]+'a')%26);
}
if(ss.back()==t.back())
cout<<"da\n";
else
cout<<"ne\n";
}
}
return 0;
}
/*
*/
