View Compilation Error

0_0_8244449_10078.cpp: In function `int main()':
0_0_8244449_10078.cpp:4: error: `o' undeclared (first use this function)
0_0_8244449_10078.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_8244449_10078.cpp:5: error: `$n' undeclared (first use this function)
0_0_8244449_10078.cpp:11: error: expected `;' before '}' token