dag.cpp: In function 'bool verif(int)': dag.cpp:30: warning: comparison between signed and unsigned integer expressions dag.cpp: In function 'int main()': dag.cpp:48: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result dag.cpp:49: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result dag.cpp:51: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result dag.cpp:54: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result