View Compilation Error

0_0_19410543_28431.cpp: In function 'void solve(int)':
0_0_19410543_28431.cpp:9:40: error: 'memset' was not declared in this scope
 #define mst(a,x) memset(a, x, sizeof(a))
                                        ^
0_0_19410543_28431.cpp:49:3: note: in expansion of macro 'mst'
   mst(f,0);
   ^
0_0_19410543_28431.cpp: In function 'int main()':
0_0_19410543_28431.cpp:9:40: error: 'memset' was not declared in this scope
 #define mst(a,x) memset(a, x, sizeof(a))
                                        ^
0_0_19410543_28431.cpp:90:4: note: in expansion of macro 'mst'
    mst(ans, 0);
    ^