foo.c:1:1: warning: data definition has no type or storage class
 n=str(input())
 ^
foo.c:1:1: warning: type defaults to 'int' in declaration of 'n' [-Wimplicit-int]
foo.c:1:3: warning: implicit declaration of function 'str' [-Wimplicit-function-declaration]
 n=str(input())
   ^~~
foo.c:1:7: warning: implicit declaration of function 'input' [-Wimplicit-function-declaration]
 n=str(input())
       ^~~~~
foo.c:1:3: error: initializer element is not constant
 n=str(input())
   ^~~
foo.c:2:1: error: expected ',' or ';' before 'n'
 n=n.repkace(" ","%20")
 ^

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