num1,operation,num2,output,flag
2,subtract,3,0,wrong sign
2,subtract,2,0,other
1,add,0,1,wrong sign
1,add,0,1,off by one
4,subtract,3,1,off by one
4,subtract,3,1,other
4,subtract,3,1,other
8,subtract,3,1,other
8,subtract,3,1,new
8,subtract,3,1,new
8,subtract,3,1,new