I am running a 2 layer CNN on the MNIST dataset and I am getting this error.

RuntimeError: size ‘[-1 x 3136]’ is invalid for input of with 131072 elements at /py/conda-bld/pytorch_1490979338030/work/torch/lib/TH/THStorage.c:55

Model used
class Net(nn.Module):
    def __init__(self):
        super(Net, self).__init__()
        self.conv1 = nn.Conv2d(1, 32, 3, padding=2)
        # conv1 = 28x28x1 => 28x28x32
        # pooling = 28x28x32 => 14x14x32
        
        self.conv2 = nn.Conv2d(32, 64, 3, padding=2)
        # conv2 = 14x14x32 => 14x14x64
        # pooling = 14x14x64 => 7x7x64
        
        self.fc1 = nn.Linear(64*7*7, 1024)
        self.fc2 = nn.Linear(1024, 10)
        
    def forward(self, x):
        x = F.max_pool2d(F.relu(self.conv1(x)), 2)
        x = F.max_pool2d(F.relu(self.conv2(x)), 2)
        # reshape Variable
        x = x.view(-1, 64*7*7) 
        x = F.relu(self.fc1(x))
        x = F.dropout(x, training=self.training)
        x = self.fc2(x)
        return x

Can anyone tell me what am I doing wrong?