/in/foo.cc: In function 'int main()':
/in/foo.cc:10:15: warning: for increment expression has no effect [-Wunused-value]
  for(i=1;i++;i<=N)
              ~^~~
/in/foo.cc:26:15: warning: for increment expression has no effect [-Wunused-value]
  for(i=1;i++;i<=N)
              ~^~~
/in/foo.cc:5:8: warning: unused variable 'n' [-Wunused-variable]
  int N,n,i,a,b,e,x=0,y,m=0;//a=期末成绩,b=班级评议成绩，c=学生干部，d=西部省份，e=论文数 
        ^
/in/foo.cc:26:11: warning: iteration 2147483646 invokes undefined behavior [-Waggressive-loop-optimizations]
  for(i=1;i++;i<=N)
          ~^~
/in/foo.cc:26:2: note: within this loop
  for(i=1;i++;i<=N)
  ^~~