/in/foo.cc: In function 'int main()':
/in/foo.cc:9:16: warning: 'r' is used uninitialized [-Wuninitialized]
    9 |         while(r!=0)
      |               ~^~~
/in/foo.cc:5:19: note: 'r' was declared here
    5 |         int x1,x2,r,m,pos1,pos2;
      |                   ^