View Compilation Error

0_0_7216557_22887.cpp: In function `int main()':
0_0_7216557_22887.cpp:18: error: `ch2' undeclared (first use this function)
0_0_7216557_22887.cpp:18: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7216557_22887.cpp:18: error: expected primary-expression before '{' token
0_0_7216557_22887.cpp:18: error: expected `;' before '{' token