0_0_34075537_24961.cpp: In function 'int solve(int)': 0_0_34075537_24961.cpp:49:9: error: 'f' was not declared in this scope mem(f,-1); ^ 0_0_34075537_24961.cpp:10:25: note: in definition of macro 'mem' #define mem(a,x) memset(a,x,sizeof a) ^