Compilare: user.cpp: In function ‘int main()’: user.cpp:46:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(st[j] < V[j].size() && V[j][st[j]] < prev) st[j]++; ^ user.cpp:47:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(st[j] == V[j].size()) ok = 0; ^ user.cpp:23:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d", &n); ^ user.cpp:25:35: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d", &v[i].val); ^