Avoid mixing singed and unsigned integers
Avoid mixing singed and unsigned integers

hvy/chainer,keisuke-umezawa/chainer,niboshi/chainer,keisuke-umezawa/chainer,hvy/chainer,wkentaro/chainer,keisuke-umezawa/chainer,okuta/chainer,hvy/chainer,keisuke-umezawa/chainer,pfnet/chainer,chainer/chainer,okuta/chainer,okuta/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,hvy/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,okuta/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,tkerola/chainer