View Compilation Error

0_0_30199392_14997.cpp: In constructor 'Matrix::Matrix()':
0_0_30199392_14997.cpp:8:35: error: 'memset' was not declared in this scope
   Matrix() { memset(a, 0, sizeof a); }
                                   ^
0_0_30199392_14997.cpp: In function 'int main()':
0_0_30199392_14997.cpp:35:16: error: 'read' was not declared in this scope
   int n = read(),a;
                ^
0_0_30199392_14997.cpp:39:5: error: 'a' was not declared in this scope
     a=ans.a[1][1]%mod;
     ^