symbolic n;

s1:={[t1, 0, 0]:1 <= t1 && 64 * t1 <= n};

s2 := {[t1, t2, 0]: 1 <= t1 && 64 * t1 <= n && t2 = t1};

s3 := {[t1, 0, t3]: 1 <= t1 && 64 * t1 <= n && t3 = t1};

s := (s1  union s2 union s3);

s;
h := Hull s;

h;

h - s;