start Take an integer 'n' as input 'n' is less than or equal to 0 'n' is equal to 1 execute this algoritm passing the value of 'n' minus 1 as input and store the result in the variable 'execution_1' Return 0 Return 1 end execute this algoritm passing the value of 'n' minus 2 as input and store the result in the variable 'execution_2' Return the value obtained by summing 'execution_1' and 'execution_2' no no yes yes