/in/foo.cc: In function 'int main()':
/in/foo.cc:10:13: warning: 'c' is used uninitialized in this function [-Wuninitialized]
  while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
        ~~~~~^~~~~~~
/in/foo.cc:9:21: note: 'c' was declared here
  int f=1,ans=0;char c;
                     ^
/in/foo.cc:9:21: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
/in/foo.cc:10:13: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
  while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
        ~~~~~^~~~~~~
/in/foo.cc:9:21: note: 'c' was declared here
  int f=1,ans=0;char c;
                     ^