Hi everyone, I'm trying to solve a dynamic problem

https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=24&problem=3637&mosmsg=Submission+received+with+ID+19929006

And this is my solution, it caught an runtime error and I dont know why. https://ideone.com/W9UHgh

Can anyone help me and explain why it caught runtime error and how to avoid runtime error ?

Thanks you.