/in/foo.c:11:1: error: unknown type name 'point'; use 'struct' keyword to refer to the type
 point maps[1005*1005];
 ^~~~~
 struct 
/in/foo.c: In function 'main':
/in/foo.c:22:9: error: unknown type name 'point'; use 'struct' keyword to refer to the type
         point st;
         ^~~~~
         struct 
/in/foo.c:23:11: error: request for member 'x' in something not a structure or union
         st.x=x1;st.y=y1;
           ^
/in/foo.c:23:19: error: request for member 'y' in something not a structure or union
         st.x=x1;st.y=y1;
                   ^
/in/foo.c:24:11: error: request for member 'step' in something not a structure or union
         st.step=0;
           ^
/in/foo.c:30:13: error: unknown type name 'point'; use 'struct' keyword to refer to the type
             point k=maps[head];
             ^~~~~
             struct 
/in/foo.c:33:17: error: request for member 'x' in something not a structure or union
             if(k.x==x2&&k.y==y2){
                 ^
/in/foo.c:33:26: error: request for member 'y' in something not a structure or union
             if(k.x==x2&&k.y==y2){
                          ^
/in/foo.c:34:32: error: request for member 'step' in something not a structure or union
                 printf("%d\n",k.step);
                                ^
/in/foo.c:38:17: error: unknown type name 'point'; use 'struct' keyword to refer to the type
                 point ss=k;
                 ^~~~~
                 struct 
/in/foo.c:39:19: error: request for member 'x' in something not a structure or union
                 ss.x=k.x+num_x[i];
                   ^
/in/foo.c:39:23: error: request for member 'x' in something not a structure or union
                 ss.x=k.x+num_x[i];
                       ^
/in/foo.c:40:19: error: request for member 'y' in something not a structure or union
                 ss.y=k.y+num_y[i];
                   ^
/in/foo.c:40:23: error: request for member 'y' in something not a structure or union
                 ss.y=k.y+num_y[i];
                       ^
/in/foo.c:41:24: error: request for member 'x' in something not a structure or union
                 if(a[ss.x-1][ss.y-1]=='0'&&ss.x<=n&&ss.x>0&&ss.y<=n&&ss.y>0){//这个是进行判断的（所以再每次直接进行坐标的上下左右移动以后，要再判断一下是否还在矩阵中）；
                        ^
/in/foo.c:41:32: error: request for member 'y' in something not a structure or union
                 if(a[ss.x-1][ss.y-1]=='0'&&ss.x<=n&&ss.x>0&&ss.y<=n&&ss.y>0){//这个是进行判断的（所以再每次直接进行坐标的上下左右移动以后，要再判断一下是否还在矩阵中）；
                                ^
/in/foo.c:41:46: error: request for member 'x' in something not a structure or union
                 if(a[ss.x-1][ss.y-1]=='0'&&ss.x<=n&&ss.x>0&&ss.y<=n&&ss.y>0){//这个是进行判断的（所以再每次直接进行坐标的上下左右移动以后，要再判断一下是否还在矩阵中）；
                                              ^
/in/foo.c:41:55: error: request for member 'x' in something not a structure or union
                 if(a[ss.x-1][ss.y-1]=='0'&&ss.x<=n&&ss.x>0&&ss.y<=n&&ss.y>0){//这个是进行判断的（所以再每次直接进行坐标的上下左右移动以后，要再判断一下是否还在矩阵中）；
                                                       ^
/in/foo.c:41:63: error: request for member 'y' in something not a structure or union
                 if(a[ss.x-1][ss.y-1]=='0'&&ss.x<=n&&ss.x>0&&ss.y<=n&&ss.y>0){//这个是进行判断的（所以再每次直接进行坐标的上下左右移动以后，要再判断一下是否还在矩阵中）；
                                                               ^
/in/foo.c:41:72: error: request for member 'y' in something not a structure or union
                 if(a[ss.x-1][ss.y-1]=='0'&&ss.x<=n&&ss.x>0&&ss.y<=n&&ss.y>0){//这个是进行判断的（所以再每次直接进行坐标的上下左右移动以后，要再判断一下是否还在矩阵中）；
                                                                        ^
/in/foo.c:42:23: error: request for member 'step' in something not a structure or union
                     ss.step=k.step+1;
                       ^
/in/foo.c:42:30: error: request for member 'step' in something not a structure or union
                     ss.step=k.step+1;
                              ^
/in/foo.c:45:25: error: request for member 'x' in something not a structure or union
                     a[ss.x-1][ss.y-1]='1';
                         ^
/in/foo.c:45:33: error: request for member 'y' in something not a structure or union
                     a[ss.x-1][ss.y-1]='1';
                                 ^
/in/foo.c:14:13: warning: unused variable 'j' [-Wunused-variable]
     int n,i,j;
             ^