Input of Unkown Size

[Script Coder]

I am solving problem, where I need to perform the same operation of an unknown number of test cases.
Input:

10 2
20 3
54 1

Output:

20
60
54

My problem is I do not know how to know when to stop reading input.

[JLBorges]

So what's the problem?

void foo( std::istream& stm )
{
    int a, b ;
    while( stm >> a >> b )
    {
        // process iniput a, b
        std::cout << a*b << '\n' ;
    }
}

[Script Coder]

Thank You. Line 4 really helped.