/in/foo.cc: In function 'void floyd()':
/in/foo.cc:83:17: warning: left operand of comma operator has no effect [-Wunused-value]
      if (atlas[i+dx[k],j+dy[k]]) g[getposid(i,j)][getposid(i+dx[k],j+dy[k])]=1;
                ~^~~~~~