i want to calculate the complexity of the following code snippet

```
for(int k=0;k<n; ++k)
for(int j=0; j<k; ++j)
for(int i=0; i<j; ++i)
cout<< "Hello World" <<endl;
```

here! i got the hint! that summation of natural numbers series would be used if its correct why ?

bit confused:sad: