foo.c: In function 'F':
foo.c:10:9: warning: implicit declaration of function 'Find' [-Wimplicit-function-declaration]
   10 |   pos = Find(s1,pos, s2);
      |         ^~~~
foo.c:12:3: warning: implicit declaration of function 'Replace1' [-Wimplicit-function-declaration]
   12 |   Replace1(s1,pos, s2,s3);
      |   ^~~~~~~~
foo.c: In function 'main':
foo.c:22:2: warning: implicit declaration of function 'Replace' [-Wimplicit-function-declaration]
   22 |  Replace(s1,s2,s3);
      |  ^~~~~~~
/usr/bin/ld: /tmp/ccNi9oB0.o: in function `F':
foo.c:(.text+0x2e): undefined reference to `Replace1'
/usr/bin/ld: foo.c:(.text+0x3e): undefined reference to `Find'
/usr/bin/ld: /tmp/ccNi9oB0.o: in function `main':
foo.c:(.text.startup+0x117): undefined reference to `Replace'
collect2: error: ld returned 1 exit status

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