Compilare: main.cpp: In function 'int main()': main.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0 ; j < v[i - 1].size() && j < v[i].size() && v[i][j] == v[i - 1][j] ; ++ j , -- cnt); ~~^~~~~~~~~~~~~~~~~ main.cpp:20:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0 ; j < v[i - 1].size() && j < v[i].size() && v[i][j] == v[i - 1][j] ; ++ j , -- cnt); ~~^~~~~~~~~~~~~ main.cpp:13:18: warning: unused variable 'lmax' [-Wunused-variable] int n, i, j, lmax, cnt, ok; ^~~~ main.cpp:13:29: warning: unused variable 'ok' [-Wunused-variable] int n, i, j, lmax, cnt, ok; ^~ main.cpp:11:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.in", "r", stdin); ^ main.cpp:12:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.out", "w", stdout); ^ main.cpp:14:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^