Compilare: main.cpp: In function 'int Do(int)': main.cpp:9:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ main.cpp: In function 'int main()': main.cpp:26:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < X.size(); i ++) { ~~^~~~~~~~~~ main.cpp:15:15: warning: unused variable 'a' [-Wunused-variable] int i, j, x, a; ^ main.cpp:16:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("excel.in","r",stdin); ^ main.cpp:17:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("excel.out","w",stdout); ^