#include <iostream>
#include <cstdio>
using namespace std;
int n, cnt, v[99];
char a;
int main() {
	cin>>n;
	while(n--) {
		cin>>a;
		if(!v[a]) cnt++;
		v[a] = 1;
	}
	cout<<(cnt==3 ? "Three" : "Four");
	return 0;
}