View Compilation Error

0_0_21807755_12750.cpp: In function 'void init()':
0_0_21807755_12750.cpp:10:32: error: 'memset' was not declared in this scope
     memset(head,-1,sizeof(head));
                                ^
0_0_21807755_12750.cpp: In function 'int main()':
0_0_21807755_12750.cpp:28:19: error: 'scanf' was not declared in this scope
     scanf("%d",&ca);
                   ^
0_0_21807755_12750.cpp:49:33: error: 'Dinic_flow' was not declared in this scope
         int ans = Dinic_flow(s,t);
                                 ^
0_0_21807755_12750.cpp:50:32: error: 'printf' was not declared in this scope
         printf("Case %d: ",cc++);
                                ^