../programs/54820.cpp: In function 'int main()':
../programs/54820.cpp:7: error: 'ifstream' was not declared in this scope
../programs/54820.cpp:7: error: expected `;' before 'cin'
../programs/54820.cpp:8: error: 'ofstream' was not declared in this scope
../programs/54820.cpp:8: error: expected `;' before 'cout'
../programs/54820.cpp:10: error: 'cin' was not declared in this scope
../programs/54820.cpp:14: error: 'swap' was not declared in this scope
../programs/54820.cpp:16: error: 'cout' was not declared in this scope
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