0_0_17174144_27532.c: In function 'prime_1':
0_0_17174144_27532.c:5:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
for(int i=2;i<=sqrt(double(n));++i)
^
0_0_17174144_27532.c:5:2: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_17174144_27532.c:5:22: error: expected expression before 'double'
for(int i=2;i<=sqrt(double(n));++i)
^
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