#include <string> 
#include <iostream>

using namespace std;

bool validate(std::string var);

int main(int argc, const char *argv[])
{
    string var; 
    cin >> var;
    if(validate(var))
        cout << "True" << endl;
    else 
        cout << "False" << endl;
    return 0;
}


bool validate(std::string var)
{
    int state = 0;

    for(int i = 0; i < var.length(); i++)
    {
        char current = var[i]; 
        switch(state)
        {
            case 0:
                if(current == 'b')
                    state = 1;
                else if(current == 'a')
                    state = 2;
                else 
                    return false;
                break;

            case 1:
                if(current == 'a')
                    state = 2;
                else if(current == 'c')
                    state = 3;
                else 
                    return false;
                break;
            case 2:
                if(current == 'b')
                    state = 1;
                else 
                    return false;
                break;
            case 3:
                if(current == 'a')
                    state = 2;
                else 
                    return false;
                break;
        }
    }
    return true;
}