View Compilation Error

0_0_18442339_20016.cpp: In function 'void solve(int)':
0_0_18442339_20016.cpp:41:27: error: 'memset' was not declared in this scope
  memset(F[x],0,sizeof F[x]);
                           ^
0_0_18442339_20016.cpp: In function 'int main()':
0_0_18442339_20016.cpp:63:26: error: 'memset' was not declared in this scope
   memset(vis,0,sizeof vis);
                          ^