0_0_37837089_10628.cpp: In function 'void solve()': 0_0_37837089_10628.cpp:50:8: error: 'a' was not declared in this scope ms(a, 0); ^ 0_0_37837089_10628.cpp:30:25: note: in definition of macro 'ms' #define ms(a, b) memset(a, b, sizeof a) ^