set key reverse Left outside
set term png

set xlabel "Numbers ->"
set ylabel "Execution time (seconds)->"
set title "Comparaisin of 4 Algorithmes"

set xtics rotate

set offset 1,1,0.01,0.01

set output "Graph5.png"

plot for [i=1:4] 'Algo'.i using 1:2 title 'Algo'.i with lines

# The variable "i" takes the values 1 to 4 . So a translation of this would be:
# plot 'Algo1' using 1:2 title 'Algo1' with lines, 'Algo2' using 1:2 title 'Algo2' with lines, 'Algo3' using 1:2 title 'Algo3' with lines, 'Algo4' using 1:2 title 'Algo4' with lines,