Compilare: user.cpp: In function ‘int main()’: user.cpp:38:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (cnt=1; cnt<=v[i].size()+v[j].size(); cnt++) ^ user.cpp:40:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (a!=v[i].size() && b!=v[j].size()) ^ user.cpp:40:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (a!=v[i].size() && b!=v[j].size()) ^ user.cpp:55:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (a==v[i].size()) ^ user.cpp:19:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("triplete.in", "r", stdin); ^ user.cpp:20:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("triplete.out", "w", stdout); ^ user.cpp:21:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:24:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^