Compilare: user.cpp: In function ‘int main()’: user.cpp:35:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < v[a].size(); i++){ ^ user.cpp:11:16: warning: unused variable ‘j’ [-Wunused-variable] int n, m, i, j, a, b; ^ user.cpp:12:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d", &n, &m); ^ user.cpp:14:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d", &a, &b); ^