exp1.cpp: In function 'int main()': exp1.cpp:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result exp1.cpp:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result exp1.cpp:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result exp1.cpp:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result