Please refer to the code fragment below:

```
sum = 0; 
for( i = 0; i < n; i++ ) 
    for( j = 0; j < i * i; j++ ) 
        for( k = 0; k < j; k++ ) 
            sum++;

```

If one was to analyze the run-time of this fragment in Big-Oh Notation, what would be the most appropriate value? Would it be O(N^4)?