#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pll pair<long long, long long>
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define endl '\n'
#define ld long double
#define sz(x) static_cast<int>((x).size())
#define i5 tuple<int,int,int,int,int>
#define all(x) x.begin(), x.end()
#define iiii tuple<int, int,int,int>
#define ld long double
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
signed main(){
int n,q;cin>>n>>q;
vector<int> a(n+2, 0), b(n+2, 0);
for(int i=1;i<=n;i++){
char c;cin>>c;
a[i]=c-'a'+1;
}
for(int i=1;i<=n;i++){
char c;cin>>c;
b[i]=c-'a'+1;
}
array<int,2> sum{0, 0};
auto ev=[&](int i)->int{
int ret=b[i+1]-b[i]-(a[i+1]-a[i]);
//printf("ev %lld is %lld\n", i, ret);
return ret;
};
for(int i=0;i<=n;i++){
sum[i%2] += ev(i);
}
if(sum[0]==0 and sum[1]==0) cout<<"da\n";
else cout<<"ne\n";
for(int i=0;i<q;i++){
int p, nv;cin>>p;
char c;cin>>c;nv=c-'a'+1;
sum[p%2] -= ev(p);
sum[(p-1)%2] -= ev(p-1);
//printf("sum 1 %lld sum 0 %lld\n", sum[1], sum[0]);
a[p]=nv;
sum[p%2] += ev(p);
sum[(p-1)%2] += ev(p-1);
//printf("sum 1 %lld sum 0 %lld\n", sum[1], sum[0]);
if(sum[0]==0 and sum[1]==0)cout<<"da\n";
else cout<<"ne\n";
}
}
