View Compilation Error

0_0_12198215_20105.cpp: In function `int main()':
0_0_12198215_20105.cpp:13: error: `b' undeclared (first use this function)
0_0_12198215_20105.cpp:13: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_12198215_20105.cpp:13: error: expected `;' before "else"