How to give multiple bitmaps as inputs in gpuimage?

Question

I am pretty beginner in OpenGL in android. I am using GPUImage Android for applying filters on images. But, my fragment shader requires three input bitmaps to produce the output.

uniform sampler2D inputImageTexture;
uniform sampler2D inputImageTexture2;
uniform sampler2D inputImageTexture3;
uniform float intensity;

But as far as I know GPUImage supports GPUImageTwoInputFilter. So, what program should I write for giving three bitmaps to the same shader. Or there is any simple way I can use OpenGL for this task.