let input = require('fs').readFileSync('/dev/stdin', 'utf8');
let [T, ...X] = input.split(/\s/).map(v => Number(v));
X = [0, ...X];
X.pop();
const R = X.every((v, i) => (i == X.length - 1) || (Math.abs(X[i + 1] - v) == 1));
console.log(R ? 'T' : 'F');