diff --git a/SCR3.1/TP4/Exo1/Rebours b/SCR3.1/TP4/Exo1/Rebours
new file mode 100755
index 0000000..37d6bdb
Binary files /dev/null and b/SCR3.1/TP4/Exo1/Rebours differ
diff --git a/SCR3.1/TP4/Exo1/Rebours.c b/SCR3.1/TP4/Exo1/Rebours.c
new file mode 100644
index 0000000..90ce52c
--- /dev/null
+++ b/SCR3.1/TP4/Exo1/Rebours.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[]) 
+{
+    int n = (int)strtol(argv[1], NULL,0);
+    int pid = getpid();
+    printf("%d: debut\n", pid);
+
+    for (int i = n; i > 0; i--) {
+        printf("%d: %d\n", pid, i);
+        sleep(1);
+    }
+    
+    printf("%d: fin\n", pid);
+
+    return 0;
+}
diff --git a/SCR3.1/TP4/Exo2/parexec b/SCR3.1/TP4/Exo2/parexec
new file mode 100755
index 0000000..ee5a9cd
Binary files /dev/null and b/SCR3.1/TP4/Exo2/parexec differ
diff --git a/SCR3.1/TP4/Exo2/parexec.c b/SCR3.1/TP4/Exo2/parexec.c
new file mode 100644
index 0000000..cad02cd
--- /dev/null
+++ b/SCR3.1/TP4/Exo2/parexec.c
@@ -0,0 +1,20 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <string.h>
+
+int main(int argc, char *argv[]) {
+    int n = argc - 2;
+    pid_t pids[n];
+
+    for (int i = 0; i < n; i++) 
+    {
+        pids[i] = fork();
+    }
+    for (int i = 0; i < n; i++) 
+    {
+        waitpid(pids[i], NULL, 0);
+    }
+    return 0;
+}
diff --git a/SCR3.1/TP4/Exo2/rebour.c b/SCR3.1/TP4/Exo2/rebour.c
new file mode 100644
index 0000000..4b8cd74
--- /dev/null
+++ b/SCR3.1/TP4/Exo2/rebour.c
@@ -0,0 +1,20 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char* argv[])
+{
+	assert(argc == 2);
+
+	int value = strtol(argv[1], NULL, 0);
+	pid_t p =  getpid();
+	printf("%d: debut\n",p);
+	for(int i = value; i>0; i--){
+		printf("%d: %d\n",p,i);
+		sleep(1);
+	}
+	printf("%d: fin\n",p);
+	return EXIT_SUCCESS;
+
+}
diff --git a/SCR3.1/TP4/Exo2/rebours b/SCR3.1/TP4/Exo2/rebours
new file mode 100755
index 0000000..e14f094
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