I'm using cloud formation to create a VPC. And it fails when it gets to creating the subnets. I checked and I believe the subnets to be valid. Though my networking knowledge is somewhat lacking. 

This is the error I get:

```
00:46:49 UTC-0400   CREATE_FAILED   AWS::EC2::Subnet    SubnetA The CIDR '172.16.64.0/16' is invalid.

```

00:46:49 UTC-0400 CREATE\_IN\_PROGRESS AWS::EC2::RouteTable RouteTable Resource creation Initiated
00:46:49 UTC-0400 CREATE\_FAILED AWS::EC2::Subnet SubnetB The CIDR '197.16.128.0/16' is invalid.

And this is the template I'm trying to use:

```
---
AWSTemplateFormatVersion: 2010-09-09
Resources:
  VPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: 172.16.0.0/18
      EnableDnsSupport: true
      EnableDnsHostnames: true
      InstanceTenancy: default
      Tags:
      - Key: Name
        Value: JF-Staging-VPC
  InternetGateway:
     Type: AWS::EC2::InternetGateway
  VPCGatewayAttachment:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      VpcId: !Ref VPC
      InternetGatewayId: !Ref InternetGateway
  SubnetA:
     Type: AWS::EC2::Subnet
     Properties:
       AvailabilityZone: us-east-1a
       VpcId: !Ref VPC
       CidrBlock: 172.16.64.0/16
       MapPublicIpOnLaunch: False
  SubnetB:
      Type: AWS::EC2::Subnet
      Properties:
        AvailabilityZone: us-east-1b
        VpcId: !Ref VPC
        CidrBlock: 197.16.128.0/16
        MapPublicIpOnLaunch: False
  RouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref VPC
  InternetRoute:
    Type: AWS::EC2::Route
    DependsOn: InternetGateway
    Properties:
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref InternetGateway
      RouteTableId: !Ref RouteTable
  SubnetARouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref RouteTable
      SubnetId: !Ref SubnetA
  SubnetBRouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      RouteTableId: !Ref RouteTable
      SubnetId: !Ref SubnetB
  SecurityGroupSSH:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupName: "SSH Group"
      GroupDescription: "SSH traffic in, all traffic out."
      VpcId: !Ref VPC
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: '22'
          ToPort: '22'
          CidrIp: 0.0.0.0/0
      SecurityGroupEgress:
        - IpProtocol: -1
          CidrIp: 0.0.0.0/0
  SecurityGroupWeb:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupName: "Web Group"
      GroupDescription: "Web traffic in, all traffic out."
      VpcId: !Ref VPC
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: '80'
          ToPort: '80'
          CidrIp: 0.0.0.0/0
      SecurityGroupEgress:
        - IpProtocol: -1
          CidrIp: 0.0.0.0/0
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: '443'
          ToPort: '443'
          CidrIp: 0.0.0.0/0
      SecurityGroupEgress:
        - IpProtocol: -1
          CidrIp: 0.0.0.0/0
Metadata:
  VPC:
    Description: "Creating the JF Staging VPC"
  InternetGateway:
    Description: "Creating an Internet Gateway"

```

Can someone let me know where I'm going wrong and how to correct this?