#include<bits/stdc++.h>
using lint=long long;
void cmx(lint&x,lint y){if(x<y)x=y;}
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint n;std::cin>>n;
    std::vector<lint>a(42);
    for(lint i=14;i<28;i++){
        char c;std::cin>>c;
        a.at(i)=c=='o';
    }
    std::vector<lint>b;
    for(lint i=0,j=1;j<=42;j++){
        if(j<42&&a.at(j-1)==a.at(j))continue;
        b.push_back(j-i);
        i=j;
    }
    lint sz=b.size();
    lint ans=std::max(b.at(1),b.at(sz-2))+n;
    for(lint i=2;i<sz-1;i+=2){
        cmx(ans,b.at(i)<=n?b.at(i-1)+b.at(i)+b.at(i+1):n+std::max(b.at(i-1),b.at(i+1)));
    }
    std::cout<<ans<<'\n';
}