Algorithm Analysis question

Given the following source code where n = number of data points:

for( int i = 0; i < n; ++i) { // cost for line?

for( int j = 0; j < n; ++j) { // cost for line?

sum += i*j; // cost for line?

}

}

Assign a cost to each line which will determine the cost function T(n): T(n) = ?