View Compilation Error

0_0_11348824_12881.cpp: In function `bool solve(int)':
0_0_11348824_12881.cpp:24: error: `n' undeclared (first use this function)
0_0_11348824_12881.cpp:24: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_11348824_12881.cpp:26: error: `str' undeclared (first use this function)