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|\( \overrightarrow{c}\)|.