Pascal. Find the product of integers from a to b, where a and b are entered from the keyboard.

program zz1;
var a, b, r, i: int64; // set variables of integer type
begin
write (‘enter the first number’); // enter the first number from the keyboard
read (a);
write (‘enter the second number’); // enter the second number from the keyboard
read (b);
r: = 1; // set the initial value for the product
for i: = a to b do // organize a loop in which we iterate over all the numbers from a to b
r: = r * i; // calculate the product of numbers from a to b by the formula
write (‘product of numbers from’, a, ‘to’, b, ‘=’, r); // display the answer
end.