a entier
b entier

c entier

debut

a = 5
b = 7

c = a           //c = 5
a = b           //a = 7
b = c           //b = 5


fin

-----------------------------

a entier
b entier

debut

a = 5
b = 7

b = b - a       //b = 2
a = a + b       //a = 7
b = a - b       //b = 5


fin