square Madness

#include <iostream>

const int maxCord = 9;
int a,b,c,d;
char input='x';

using namespace std;
char block=' ';
int main ()
{
    do
    {
    cout<<"Enter figure a, b, c, d, e, f, g, h, i, j or x to exit\n";
    cin>>input;
    if (input == 'a') {a=-1; b=1; c=1; d=1;}
    else if (input == 'b') {a=-1; b=-1; c=1; d=-1;}
    else if (input == 'c') {a=-1; b=1; c=-1; d=1;}
    else if (input == 'd') {a=1; b=-1; c=1; d=-1;}
    else if (input == 'e') {a=-1; b=1; c=1; d=-1;}
    else if (input == 'f') {a=-1; b=-1; c=1; d=1;}
    else if (input == 'g') {a=-1; b=-1; c=-1; d=-1;}
    else if (input == 'h') {a=1; b=1; c=1; d=1;}
    else if (input == 'i') {a=-1; b=-1; c=-1; d=1;}
    else if (input == 'j') {a=1; b=-1; c=1; d=1;}
    else if (input == 'x') {break;}
    else {cout<<"Incorrect input\n"; continue; };

    for (int y=0; y < maxCord; y++)
    {
        for (int x = 0; x < maxCord; x++)
        {
            block=' ';
//          if ( (a*(x+y) >= a*(maxCord-1) && b*x >= b*y) || (c*(x+y) >= c*(maxCord-1) && d*x >= d*y))
            if ( (a*y >= a*maxCord/2 ) &&  ( b*x  >= b*maxCord/2) || ( c*y >= c*maxCord/2) &&  (d*x >= d*maxCord/2) )
            {
                block='*';
            }
            cout<<' '<<block<<' ';
        }
    cout << endl;
    }
    cout << endl;
    }
    while (input!='x');
}