Compilare: main.c: In function 'main': main.c:169:11: warning: implicit declaration of function 'read' [-Wimplicit-function-declaration] iindex = read(0, input, 2000000); ^~~~ main.c:193:2: warning: implicit declaration of function 'write' [-Wimplicit-function-declaration] write(1, output, oindex); ^~~~~ main.c:159:17: warning: unused variable 'buf' [-Wunused-variable] char line[32], buf[32]; ^~~ main.c:159:7: warning: unused variable 'line' [-Wunused-variable] char line[32], buf[32]; ^~~~ main.c:163:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen( "trie.in", "r", stdin ); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:164:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen( "trie.out", "w", stdout ); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~