Compilare: main.cpp: In function 'int main()': main.cpp:71:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(l=0; l<vec[j].size(); l++) ~^~~~~~~~~~~~~~ main.cpp: In function 'char next_char()': main.cpp:14:32: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buff,1,val,stdin); ^ main.cpp: In function 'int main()': main.cpp:40:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("deletegcd.in","r",stdin); ^ main.cpp:41:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("deletegcd.out","w",stdout); ^