Here is  :
b= 3
n=1000
input=torch.rand(b,n,n)

first_layer_node_1=Relu(w1*w2*w3*input[0])# n by n
first_layer_node_2=Relu(w1*w2*w3*input[1])# n by n
first_layer_node_3=Relu(w1*w2*w3*input[2])# n by n


output_layer=Relu(w1*first_layer_node_1+w2*first_layer_node_2+w3*first_layer_node_3)# n by n

Thank you