Compilare: user.cpp: In function ‘void read()’: user.cpp:23:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a.size(); i++) ^ user.cpp:35:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a.size(); i++) ^ user.cpp:38:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<a[i].size(); j++) ^ user.cpp: In function ‘void sp(int)’: user.cpp:49:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (; i<a.size(); i++) ^ user.cpp:53:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i==a.size() || a[i][x]==0) ^ user.cpp: In function ‘void adun(int)’: user.cpp:64:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=x+1; i<a.size(); i++) ^ user.cpp:67:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=x; j<a[i].size(); j++) ^ user.cpp: In function ‘void solve()’: user.cpp:76:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a.size(); i++) ^ user.cpp: In function ‘void write()’: user.cpp:93:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<a.size(); j++) ^ user.cpp: At global scope: user.cpp:103:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^