Regarding this question


https://hack.codingblocks.com/app/practice/1/737/problem
sir can you tell me the mistake in my program

Hi Sameer. This approach wont work here. As it is mentioned that value of integers can be upto 1000 so 1000! wont fit even in long long int(as it has a range upto 10^18)
for this refer https://www.geeksforgeeks.org/factorial-large-number/
From here u can read how to calculate factorial of large numbers

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