value cannot be converted to type int without overflow

[gosling123456]

Traceback (most recent call last):
File "train.py", line 216, in
main(args)
File "train.py", line 154, in main
confmat = evaluate(model, val_loader, device=device, num_classes=num_classes)
File "/home/ma-user/work/SEG/deep-learning-for-image-processing/pytorch_segmentation/deeplab_v3/train_utils/train_and_eval.py", line 29, in evaluate
confmat.update(target.flatten(), output.argmax(1).flatten())
File "/home/ma-user/work/SEG/deep-learning-for-image-processing/pytorch_segmentation/deeplab_v3/train_utils/distributed_utils.py", line 88, in update
self.mat += torch.bincount(inds, minlength=n**2).reshape(n, n)
RuntimeError: value cannot be converted to type int without overflow