View Compilation Error

0_0_5984816_25290.cpp: In function `void Init()':
0_0_5984816_25290.cpp:15: error: `minus' undeclared (first use this function)
0_0_5984816_25290.cpp:15: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_5984816_25290.cpp: In function `void solve(int)':
0_0_5984816_25290.cpp:20: error: `minus' undeclared (first use this function)