599 B | 599 chars
#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef vector <ll> llv1;
typedef unsigned int uint;
typedef vector <ull> ullv1;
typedef vector <vector <ull>> ullv2;
ll N,ar[110000],K;
int z = 0;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> N;
for(int x=1; x<=N; x++) cin >> ar[x];
cin >> K;
for(int x=1; x<=N; x++) {
if(ar[x] < K*x) z|=1;
if(ar[x] > K*x) z|=2;
if(ar[x] == K*x) z|=3;
}
if(z==3) {
cout << "T";
}
else cout << "F";
}