Problem $1$: The Shift Cipher is a type of Caesar Cipher, which is a simple substitution cipher. It works by shifting the letters of the alphabet by a certain number of places. To decrypt the given ciphertext, we need to try all possible shifts $($from $1$ to $25)$ and see which one gives a meaningful plaintext. In this case, the shift is $10$ and the decrypted plaintext is "WELCOMETOCRYPTOGRAPHY".