#include #include #include #include #include #include using namespace std; using uint = unsigned int; using ull = unsigned long long; #define P 1000000007 ull S( const ull& N , const ull& M , const ull& K ); int main() { ull N; ull M; ull K; cin >> N; cin >> M; cin >> K; cout << S( N , M , K ) << endl; return 0; } ull A1( const ull& M , const ull& K ); ull A2( const ull& M , const ull& K ); ull A3( const ull& M , const ull& K ); uint Comb( const ull& K , const ull& k ); ull S( const ull& N , const ull& M , const ull& K ) { if( K == 1 ){ return 0; } static ull n = 0; static ull m = 0; static vector s{}; if( n != N || m != M ){ n = N; m = M; s.clear(); s.push_back( 0 ); s.push_back( 0 ); } else if( K < s.size() ){ return s[K]; } ull a; if( N == 1 ){ a = A1( M , K ); } else if( N == 2 ){ a = A2( M , K ); } else { a = A3( M , K ); } for( ull k = 2 ; k < K ; k++ ){ ull s = ( S( N , M , k ) * (ull)( Comb( K , k ) ) ) % P; if( a >= s ){ a -= s; } else { a = ( a + ( P - s ) ) % P; } } while( s.size() < K ){ s.push_back( 0 ); } s.push_back( a ); return a; } ull A1( const ull& M , const ull& K ) { // N == 1 // A_M = K * ( K - 1 ) ^ { M - 1 } if( M == 1 ){ return K; } return ( A1( M - 1 , K ) * ( K - 1 ) ) % P; } ull A2( const ull& M , const ull& K ) { // K < 2 // A_M = 0 if( K == 1 ){ return 0; } // N == 2 && K >= 2 // A_M // = K * ( K - 1 ) * ( ( K - 1 ) + ( K - 1 ) * ( K - 2 ) ) ^ { M - 1 } // = K * ( K - 1 ) * ( K - 1 ) ^ { 2 * ( M - 1 ) } // = K * ( K - 1 ) ^ { 3 * ( M - 1 ) } if( M == 1 ){ return K; } static ull k = 0; static ull m = 0; if( k != K ){ k = K; m = ( ( ( ( K - 1 ) * ( K - 1 ) ) % P ) * ( K - 1 ) ) % P; } return ( A2( M - 1 , K ) * m ) % P; } ull B( const ull& M , const ull& K ); ull C( const ull& M , const ull& K ); ull A3( const ull& M , const ull& K ) { // N == 3 // A_M = B_M + C_M return ( B( M , K ) + C( M , K ) ) % P; } ull B( const ull& M , const ull& K ) { // K < 2 // A_M = 0 if( K == 1 ){ return 0; } // B_1 = K * ( K - 1 ) // B_{ M + 1 } // = B_M * ( ( K - 1 ) + ( K - 2 ) ^ 2 ) // + C_M * ( ( K - 1 ) + ( K - 3 ) * ( K - 2 ) ) // = B_M * ( K ^ 2 - 3 * K + 3 ) // + C_M * ( K ^ 2 - 4 * K + 5 ) static ull k = 0; static ull m1 = 0; static ull m2 = 0; static vector s{}; if( k != K ){ k = K; m1 = ( ( ( K - 3 ) * K ) + 3 ) % P; m2 = ( ( ( K - 3 ) * K ) + 5 - K ) % P; s.clear(); s.push_back( 0 ); s.push_back( ( K * ( K - 1 ) ) % P ); } if( M < s.size() ){ return s[M]; } ull a = ( ( B( M - 1 , K ) * m1 ) % P + ( C( M - 1 , K ) * m2 ) % P ) % P; s.push_back( a ); return a; } ull C( const ull& M , const ull& K ) { // K < 3 // A_M = 0 if( K < 3 ){ return 0; } // C_1 = K * ( K - 1 ) * ( K - 2 ) // C_{ M + 1 } // = B_M * ( ( K - 2 ) + ( K - 2 ) * ( K - 3 ) + ( K - 2 ) * ( ( K - 2 ) + ( K - 3 ) ^ 2 ) ) // + C_M * ( ( K - 2 ) + ( K - 2 ) * ( K - 3 ) + ( K - 2 ) ^ 2 + ( K - 3 ) * ( ( K - 2 ) + ( K - 3 ) ^ 2 ) ) // = B_M * ( ( K - 2 ) * ( K ^ 2 - 4 * K + 5 ) ) // + C_M * ( 2 * ( K - 2 ) ^ 2 + ( K - 3 ) * ( ( K - 2 ) + ( K - 3 ) ^ 2 ) ) static ull k = 0; static ull m1 = 0; static ull m2 = 0; static vector s{}; if( k != K ){ k = K; m1 = ( ( K - 2 ) * ( ( ( K - 3 ) * K + 5 - K ) % P ) ) % P; m2 = ( 2 * ( ( ( K - 2 ) * ( K - 2 ) ) % P ) + ( ( K - 3 ) * ( ( ( K - 2 ) + ( K - 3 ) * ( K - 3 ) ) % P ) ) % P ) % P; s.clear(); s.push_back( 0 ); s.push_back( ( ( ( K * ( K - 1 ) ) % P ) * ( K - 2 ) ) % P ); } if( M < s.size() ){ return s[M]; } ull a = ( ( B( M - 1 , K ) * m1 ) % P + ( C( M - 1 , K ) * m2 ) % P ) % P; s.push_back( a ); return a; } uint Comb( const ull& K , const ull& k ) { if( k == 0 || k == K ){ return 1; } if( K == 1 ){ return 1; } static vector > c{}; while( c.size() <= K ){ c.push_back( vector() ); } vector& v = c[K]; while( v.size() <= k ){ v.push_back( 0 ); } if( v[k] != 0 ){ return v[k]; } v[k] = ( Comb( K - 1 , k - 1 ) + Comb( K - 1 , k ) ) % P; return v[k]; }