ALGOSPOT - Merciful Algospot

http://algospot.com/judge/problem/read/MERCY
CODECHEF - Prime Generator

http://www.codechef.com/problems/PRIME1
CODECHEF - Bytelandian gold coins

http://www.codechef.com/problems/COINS
CODECHEF - Transform the Expression

http://www.codechef.com/problems/ONP/