foo.cpp: In function 'int go(int, int, int, int)':
foo.cpp:7:5: warning: unused variable 'tmp' [-Wunused-variable]
 int tmp=0,dx1=x+step[dr][0],dy1=y+step[dr][1],dx2=x+step[(dr+1)%4][0],dy2=y+step[(dr+1)%4][1],d1,d2;
     ^
foo.cpp:7:95: warning: unused variable 'd1' [-Wunused-variable]
 int tmp=0,dx1=x+step[dr][0],dy1=y+step[dr][1],dx2=x+step[(dr+1)%4][0],dy2=y+step[(dr+1)%4][1],d1,d2;
                                                                                               ^
foo.cpp:7:98: warning: unused variable 'd2' [-Wunused-variable]
 int tmp=0,dx1=x+step[dr][0],dy1=y+step[dr][1],dx2=x+step[(dr+1)%4][0],dy2=y+step[(dr+1)%4][1],d1,d2;
                                                                                                  ^
foo.cpp: In function 'int main()':
foo.cpp:14:25: error: 'memset' was not declared in this scope
 memset(cnt,0,sizeof(cnt));
                         ^