View Compilation Error

0_0_15063555_14651.cpp: In function 'void TwoSat()':
0_0_15063555_14651.cpp:116:29: error: 'memset' was not declared in this scope
     memset(low,0,sizeof(low));     
                             ^
0_0_15063555_14651.cpp: In function 'int main()':
0_0_15063555_14651.cpp:166:40: error: 'memset' was not declared in this scope
             memset(head,-1,sizeof(head));   
                                        ^