View Compilation Error

0_0_11995316_14911.cpp: In function `int main()':
0_0_11995316_14911.cpp:13: error: `isPrime' undeclared (first use this function)
0_0_11995316_14911.cpp:13: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_11995316_14911.cpp: In function `int isPrime(int)':
0_0_11995316_14911.cpp:21: error: `int isPrime(int)' used prior to declaration