Compilare: user.cpp: In function ‘int main()’: user.cpp:131:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < v[i].size(); j++){ ~~^~~~~~~~~~~~~ user.cpp: In function ‘int num()’: user.cpp:21:37: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(sir, 1, DIM1, fin); ^ user.cpp:30:37: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(sir, 1, DIM1, fin); ^ user.cpp: In function ‘int main()’: user.cpp:111:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &n); ^ user.cpp:112:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%s", s + 1); ^ user.cpp:113:29: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(sir, 1, DIM1, fin); ^