local ffi = require 'ffi'

print((function (f, n)
	local a,r,t = ffi.new("int8_t[?]",n),0,0
	for i=0,n-1 do a[i]=1 end
	for _=1,n do f(a) end
	for i=0,n-1 do if a[i]==1 then r,t=i,t+1 end end
	return t==1 and r+1 or -1
end)(function (a)
	local i=0
	for e in io.stdin:read("*l"):gmatch("[%-%w]+") do 
		if e~="-" and e~="nyanpass" then a[i]=0 end
		i=i+1
	end
end, tonumber(io.stdin:read("*l"))))