'int' is essential to start programming?
You mean the 'int' before 'main()'? Well, kinda. That int before main means that the function 'main' returns a integer (look at the 'return 0' line), but you can change that to another types, like 'void' (meaning that the function returns nothing). You always need to write what the function returns, otherwise, the code will not compile. You will see more about that later, so you dont need to care about those stuff.
Thank you..@Eduardo Thales Maschio Soares