/in/foo.cc: In function 'int main()':
/in/foo.cc:6:10: warning: statement has no effect [-Wunused-value]
     for(n>=1;n<=12;n++);
         ~^~~
/in/foo.cc:7:10: warning: statement has no effect [-Wunused-value]
     for(a>=1;a<=n;a++);
         ~^~~
/in/foo.cc:8:10: warning: statement has no effect [-Wunused-value]
     for(b>=1;b<=n;b++);
         ~^~~
/in/foo.cc:9:10: warning: statement has no effect [-Wunused-value]
     for(v>=1;v<=500000;v++);
         ~^~~
/in/foo.cc:6:15: warning: 'n' is used uninitialized in this function [-Wuninitialized]
     for(n>=1;n<=12;n++);
              ~^~~~