concurs1.cpp: In function 'int add(int)': concurs1.cpp:16: warning: no return statement in function returning non-void concurs1.cpp: In function 'int main()': concurs1.cpp:27: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result concurs1.cpp:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result concurs1.cpp:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result concurs1.cpp:30: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/ccy7JUBz.o: In function `main': concurs1.cpp:(.text+0x6a): warning: the `gets' function is dangerous and should not be used.