Compilare: main.cpp: In function 'int main()': main.cpp:18:21: warning: unused variable 'len' [-Wunused-variable] int n , i , j , len , elem = 0 , x , y; ^~~ main.cpp:19:25: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&n); ^ main.cpp:22:39: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&a[i][j]); ^