## Euler's Totient FunctionIf you are given a number N, you have to determine how many integers between 1 and N have a GCD of 1 with N. |

## Binary SearchFinding a number in a sorted array using binary search. |

## Sieve of EratosthenesA beginner's number theory tutorial on Sieve of Eratosthenes. |

## Faster I/OLearn how to use faster I/O methods in sport programming. |