View Compilation Error

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)
                         ^