Compilare: main.cpp: In function 'int main()': main.cpp:57:32: warning: format '%d' expects argument of type 'int', but argument 3 has type 'std::vector<std::vector<int> >::size_type {aka long unsigned int}' [-Wformat=] fprintf(fo,"%d\n", M.size()); ^ main.cpp:48:18: warning: unused variable 'j' [-Wunused-variable] int i, x, y, j; ^ main.cpp:46:30: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d%d", &n, &m); ^ main.cpp:50:33: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d%d",&x, &y); ^