foo.cpp:16:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^
foo.cpp: In function 'int main()':
foo.cpp:18:20: error: 'scanf' was not declared in this scope
 scanf("%d %d",&n,&m);
                    ^
foo.cpp:20:21: error: 'memset' was not declared in this scope
 memset(h,0,sizeof(h));
                     ^
foo.cpp:41:43: error: 'printf' was not declared in this scope
 for (i=100; i>=1; i--) {printf("%d",ans[i]); if (i%10==1) printf("\n");}
                                           ^