#include <bits/stdc++.h> using namespace std; const int N = 5e5 + 10; int t[N][30], n, ptr, sub[N], hv[N]; bool leaf[N]; vector<char> c; void dfs( int u ) { sub[u] = 0; for( int i = 0 ; i < 26 ; i++ ) { int v = t[u][i]; if( v == -1 ) continue ; dfs( v ); if( sub[v] + 1 > sub[u] ) hv[u] = i, sub[u] = sub[v] + 1; } } void solve( int u ) { if( leaf[u] ) c.emplace_back('P'); for( int i = 0 ; i < 26 ; i++ ) { int v = t[u][i]; if( v == -1 || i == hv[u] ) continue ; c.emplace_back( i + 'a' ); solve( v ); } if( hv[u] != -1 ) { c.emplace_back( hv[u] + 'a' ); solve( t[u][hv[u]] ); } c.emplace_back( '-' ); } int main() { memset( t, -1, sizeof t ); memset( hv, -1, sizeof hv ); scanf("%d",&n); for( int i = 1 ; i <= n ; i++ ) { char s[30]; scanf(" %s",s+1); int cptr = 0; for( int j = 1 ; j <= strlen( s+1 ) ; j++ ) { int &pos = t[cptr][s[j]-'a']; if( pos == -1 ) pos = ++ptr; cptr = pos; } leaf[cptr] = true; } dfs( 0 ); solve( 0 ); while( !c.empty() && c.back() == '-' ) c.pop_back(); printf("%d\n",c.size()); for( int i = 0 ; i < ( int )c.size() ; i++ ) printf("%c\n",c[i]); return 0; }

printer.cpp: In function 'int main()':
printer.cpp:43:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for( int j = 1 ; j <= strlen( s+1 ) ; j++ ) {
                          ~~^~~~~~~~~~~~~~~~
printer.cpp:53:27: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<char>::size_type {aka long unsigned int}' [-Wformat=]
     printf("%d\n",c.size());
                   ~~~~~~~~^
printer.cpp:38:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
printer.cpp:41:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf(" %s",s+1);
         ~~~~~^~~~~~~~~~~