Compilare: main.cpp: In function 'int main()': main.cpp:144:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0 ; j < val[i].size() ; j++) ~~^~~~~~~~~~~~~~~ main.cpp:180:13: warning: unused variable 'x' [-Wunused-variable] int x = possible (a[w.back().first][w.back().second] , w.back().first , w.back().second); ^ main.cpp:129:30: 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:132:39: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&a[i][j]); ^