设向量\( \overrightarrow{a},\overrightarrow{b},\overrightarrow{c}​\)满足\( \overrightarrow{a}＋\overrightarrow{b}＋\overrightarrow{c}​\)=\( \overrightarrow{0},​\)(\( \overrightarrow{a}－\overrightarrow{b}​\))⊥\( \overrightarrow{c},\overrightarrow{a}​\)⊥\( \overrightarrow{b},​\)若|\( \overrightarrow{a}​\)|=1\( ,​\)求|\( \overrightarrow{c}​\)|.