Compilare: user.cpp: In function ‘int main()’: user.cpp:41:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < C.size(); i++){ ^ user.cpp:44:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j + 1 < C[i].size(); j++){ ^ user.cpp:53:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < C.size(); i++){ ^ user.cpp:58:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j + 1 < C[i].size(); j++) ^ user.cpp:20:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d", &n); ^ user.cpp:21:78: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i = 1; i <= n; i++) fscanf(fi,"%d", &a[i]), fr[a[i]].push_back(i); ^ user.cpp:22:78: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i = 1; i <= n; i++) fscanf(fi,"%d", &b[i]), fr[b[i]].push_back(i); ^