View Compilation Error

221986_0_13245.cpp:3: error: `main' must return `int'
221986_0_13245.cpp: In function `int main(...)':
221986_0_13245.cpp:12: error: `sqrt' undeclared (first use this function)
221986_0_13245.cpp:12: error: (Each undeclared identifier is reported only once for each function it appears in.)