brunhilda.cpp: In function 'int main()':
brunhilda.cpp:19:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  freopen("in.txt" , "r" , stdin) ;
                                  ^
brunhilda.cpp:21:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d" , &n,&m ) ;
                         ^
brunhilda.cpp:24:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d" , pr+i) ;
                      ^
brunhilda.cpp:39:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d" , &val) ;
                      ^