import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

T,*X = map(int,read().split())

X = [0] + X

dx = [y - x for x,y in zip(X,X[1:])]

answer = 'T' if all(x == 1 for x in dx) else 'F'
print(answer)