Compilare: user.cpp: In function ‘int main()’: user.cpp:20:39: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( fin, "%d%d%s", &q, &n, s ); ^ user.cpp:26:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf( fin, "%s", s ); ^ user.cpp:22:17: warning: iteration 5u invokes undefined behavior [-Waggressive-loop-optimizations] c[ s[ i ] - 'a' ] = i; ^ user.cpp:21:5: note: containing loop for( int i = 0; i < lmax; ++ i ) { ^