/in/foo.c: In function 'main':
/in/foo.c:40:10: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
 b=(tx+1)+abs(tx-x)+abs(ty-y)+1;
          ^~~
/in/foo.c:5:36: warning: unused variable 'bu' [-Wunused-variable]
 {int m,n,k;int t=0,tx=0,ty=0,sum=0,bu=0,x=0,y=0,b=0;
                                    ^~