Let f:ℝ→ℝ be a continuous odd function, which vanishes exactly at one point and  f1=12.Suppose that  Fx=∫−1xftdt for all x∈−1,2 and  Gx=∫−1xtfftdtfor all  x∈−1,2.If   limx→1FxGx=114,then the value of f12 is