#include <bits/stdc++.h>
using namespace std;
int main() {
int n,x,y;
cin>>n>>x>>y;
string s;
cin>>s;
string s1=s.substr(5,3);
bool l=true;
for(int i=0;i<s1.size();i++)
{
if(s[i]!='o')
{
l=false;
break;
}
}
if(l)
{
cout<<"yes"<<endl;
}
else
{
cout<<"no"<<endl;
}
// your code goes here
return 0;
}
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