Compilare: user.cpp: In function ‘void solve(int)’: user.cpp:23:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(lin<=n){ ^ user.cpp:26:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(v[id(lin+1, col)]<val){ ^ user.cpp:36:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<=n; i++) ^ user.cpp: In function ‘int main()’: user.cpp:68:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<=n*(n+1)/2; i++) ^ user.cpp:72:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<=n; i++){ ^ user.cpp:104:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=st; i<=dr; i++) ^ user.cpp:64:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("summax.in", "r", stdin); ^ user.cpp:65:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("summax.out", "w", stdout); ^ user.cpp:66:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &t, &n, &st, &dr); ^