<Table> Treaty of Friendship, Cooperation, and Mutual Assistance <Tr> <Td_colspan="2"> Russian: Договор о дружбе, сотрудничестве и взаимной помощи </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Td_colspan="2"> Member states in 1990 (dark green) Former member states (light green) </Td> </Tr> <Tr> <Th> Formation </Th> <Td> 14 May 1955 in Warsaw, Poland </Td> </Tr> <Tr> <Th> Dissolved </Th> <Td> 1 July 1991 </Td> </Tr> <Tr> <Th> Type </Th> <Td> Military alliance </Td> </Tr> <Tr> <Th> Headquarters </Th> <Td> Moscow, Russian SFSR, Soviet Union </Td> </Tr> <Tr> <Th> Membership </Th> <Td> Albania (withdrew in 1968) Bulgaria Czechoslovakia East Germany Hungary Poland Romania Soviet Union </Td> </Tr> <Tr> <Th> Supreme Commander </Th> <Td> Petr Lushev (last) </Td> </Tr> <Tr> <Th> Chief of Combined Staff </Th> <Td> Vladimir Lobov (last) </Td> </Tr> </Table> <Tr> <Td_colspan="2"> Russian: Договор о дружбе, сотрудничестве и взаимной помощи </Td> </Tr>

When did the warsaw pact start and end
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