#include "snakelib.h"
#include<bits/stdc++.h>
using namespace std;
int k;
char x, y;
void casework(int &st, int &dr, int mid1, int mid2)
{
if(x == 's' && y == 'f')
{
st = (st + mid1) / 2 - k;
dr = mid2 + k;
}
if(x == 'b' && y == 'b')
st = mid1;
if(x == 'f' && y == 'f')
dr = mid1 + k;
if(x == 'b' && y == 'f')
{
st = mid1;
dr = mid2 + k;
}
if(x == 'b' && y == 's')
{
st = mid1;
dr = (dr + mid2) / 2 + k;
}
}
int main()
{
k = get_speed();
int st = 0;
int dr = 12121;
int qu = 13;
int minlen = 0;
while(qu)
{
int mid1 = st + (dr - st) / 3;
int mid2 = dr - (dr - st) / 3;
ask_snake(mid1, mid2, &x, &y);
--qu;
if(x == 's' && y == 's')
{
while(qu && x == 's' && y == 's')
{
minlen = max(minlen, mid2 - mid1 + 1);
mid1 = (st + mid1 - k) / 2;
mid2 = (dr + mid2 + k) / 2;
ask_snake(mid1, mid2, &x, &y);
--qu;
}
casework(st, dr, mid1, mid2);
}
else
casework(st, dr, mid1, mid2);
}
if(minlen == 0)
tell_length(minlen);
else
tell_length(dr - st + 1);
}
