for(i=0;i<=n;i++) //outer
for(i=0;i<=n;i++) //inner
for(i=0;i<=n;i++)//innermost-loop
print(GO);
Initially $i= 0$ for outer loop. then, inner loop gets executed and then innermost loop executes setting $i=0$ and executes for $n+1$ times as $i= 0$ to $i = n$, At the end when $i = n+1$ Innermost loop executes to be false. then $i++$ makes $i = n+2$ and condition for inner loop executes to be false and then for outer loop condition is checked after checking condition which evalutes to be false. So, GO is printed $n+1$ times as $i = 0$ to $i=n+1$.
So, TC $=\color{blue}{\theta(n)}$. A further interesting question would be what is the final value of $i$.
