flood.cpp: In function 'int main(int, char**)':
flood.cpp:7:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
freopen(argv[1],"r",stdin);
~~~~~~~^~~~~~~~~~~~~~~~~~~
flood.cpp:9:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&n);
~~~~~^~~~~~~~~
flood.cpp:12:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&a);
~~~~~^~~~~~~~~
flood.cpp:15:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
freopen(argv[2],"r",stdin);
~~~~~~~^~~~~~~~~~~~~~~~~~~
flood.cpp:16:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&n);
~~~~~^~~~~~~~~
flood.cpp:18:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&a);
~~~~~^~~~~~~~~