Compilare: main.cpp: In function 'int main()': main.cpp:141:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0 ; j < val[i].size() ; j++){ ~~^~~~~~~~~~~~~~~ main.cpp:126:30: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d%d",&n,&m); ^ main.cpp:129:39: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&a[i][j]); ^